Implement IDisposable pattern on HttpClient usage

The HttpClient instances are now wrapped in a using statement to properly dispose them after use. This practice prevents potential memory leaks and ensures that system resources are returned back to the system once the HttpClient instances are no longer needed, improving the system's overall efficiency and performance.

Signed-off-by: Ivandro Jao <ivandrofly@gmail.com>

src/ui/Forms/Tts/TextToSpeech.cs

@@ -933,7 +933,8 @@ namespace Nikse.SubtitleEdit.Forms.Tts
 
         private bool GenerateParagraphAudioCoqui(Subtitle subtitle, bool showProgressBar, string overrideFileName)
         {
-            var httpClient = new HttpClient();
+            using (var httpClient = new HttpClient())
+            {
                 httpClient.BaseAddress = new Uri(nikseComboBoxVoice.Text.StartsWith("http", StringComparison.OrdinalIgnoreCase) ? nikseComboBoxVoice.Text : "http://localhost:5002/api/tts");
 
                 progressBar1.Value = 0;
@@ -977,10 +978,12 @@ namespace Nikse.SubtitleEdit.Forms.Tts
 
                 return true;
             }
+        }
 
         private bool GenerateParagraphAudioAllTalk(Subtitle subtitle, bool showProgressBar, string overrideFileName)
         {
-            var httpClient = new HttpClient();
+            using (var httpClient = new HttpClient())
+            {
                 httpClient.BaseAddress = new Uri("http://127.0.0.1:7851");
 
                 progressBar1.Value = 0;
@@ -1054,6 +1057,7 @@ namespace Nikse.SubtitleEdit.Forms.Tts
 
                 return true;
             }
+        }
 
         private bool GenerateParagraphAudioElevenLabs(Subtitle subtitle, bool showProgressBar, string overrideFileName)
         {
@@ -1064,7 +1068,8 @@ namespace Nikse.SubtitleEdit.Forms.Tts
                 return false;
             }
 
-            var httpClient = new HttpClient();
+            using (var httpClient = new HttpClient())
+            {
                 httpClient.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "application/json");
                 httpClient.DefaultRequestHeaders.TryAddWithoutValidation("accept", "audio/mpeg");
                 httpClient.DefaultRequestHeaders.TryAddWithoutValidation("xi-api-key", nikseTextBoxApiKey.Text.Trim());
@@ -1131,6 +1136,7 @@ namespace Nikse.SubtitleEdit.Forms.Tts
 
                 return true;
             }
+        }
 
         private List<AzureVoiceModel> GetAzureVoices(bool useCache)
         {
@@ -1233,7 +1239,8 @@ namespace Nikse.SubtitleEdit.Forms.Tts
                 return false;
             }
 
-            var httpClient = new HttpClient();
+            using (var httpClient = new HttpClient())
+            {
                 httpClient.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "ssml+xml");
                 httpClient.DefaultRequestHeaders.TryAddWithoutValidation("accept", "audio/mpeg");
                 httpClient.DefaultRequestHeaders.TryAddWithoutValidation("X-Microsoft-OutputFormat", "audio-16khz-32kbitrate-mono-mp3");
@@ -1301,6 +1308,7 @@ namespace Nikse.SubtitleEdit.Forms.Tts
 
                 return true;
             }
+        }
 
         private void buttonOK_Click(object sender, EventArgs e)
         {
@@ -1806,7 +1814,8 @@ namespace Nikse.SubtitleEdit.Forms.Tts
 
             if (!useCache)
             {
-                var httpClient = new HttpClient();
+                using (var httpClient = new HttpClient())
+                {
                     httpClient.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "application/json");
                     httpClient.DefaultRequestHeaders.TryAddWithoutValidation("accept", "application/json");
                     var url = "https://huggingface.co/rhasspy/piper-voices/resolve/main/voices.json?download=true";
@@ -1823,6 +1832,7 @@ namespace Nikse.SubtitleEdit.Forms.Tts
 
                     File.WriteAllBytes(jsonFileName, bytes);
                 }
+            }
 
             if (File.Exists(jsonFileName))
             {
@@ -1903,7 +1913,8 @@ namespace Nikse.SubtitleEdit.Forms.Tts
 
             if (!useCache)
             {
-                var httpClient = new HttpClient();
+                using (var httpClient = new HttpClient())
+                {
                     httpClient.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "application/json");
                     httpClient.DefaultRequestHeaders.TryAddWithoutValidation("accept", "application/json");
 
@@ -1927,6 +1938,7 @@ namespace Nikse.SubtitleEdit.Forms.Tts
 
                     File.WriteAllBytes(jsonFileName, bytes);
                 }
+            }
 
             if (File.Exists(jsonFileName))
             {
@@ -1991,7 +2003,8 @@ namespace Nikse.SubtitleEdit.Forms.Tts
 
             if (!useCache)
             {
-                var httpClient = new HttpClient();
+                using(var httpClient = new HttpClient())
+                {
                     httpClient.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "application/json");
                     httpClient.DefaultRequestHeaders.TryAddWithoutValidation("accept", "application/json");
 
@@ -2010,6 +2023,7 @@ namespace Nikse.SubtitleEdit.Forms.Tts
 
                     File.WriteAllBytes(jsonFileName, bytes);
                 }
+            }
 
             if (File.Exists(jsonFileName))
             {