Fix unit tests

Author: ChaseDRedmon

src/CatBox.NET/Client/CatBox/CatBoxClient.cs

@@ -190,6 +190,7 @@ public CatBoxClient(HttpClient client, IOptions<CatboxOptions> catboxOptions)
 
         foreach (var fileUrl in urlUploadRequest.Files.Where(f => f is not null))
         {
+            ct.ThrowIfCancellationRequested();
             using var content = new MultipartFormDataContent // Disposing of MultipartFormDataContent, cascades disposal of String / Stream / Content classes
             {
                 { new StringContent(RequestType.UrlUpload), RequestParameters.Request },

src/CatBox.NET/Client/Litterbox/LitterboxClient.cs

@@ -61,6 +61,7 @@ public LitterboxClient(HttpClient client, IOptions<CatboxOptions> catboxOptions)
 
         foreach (var imageFile in temporaryFileUploadRequest.Files.Where(IsFileExtensionValid))
         {
+            ct.ThrowIfCancellationRequested();
             await using var fileStream = File.OpenRead(imageFile.FullName);
 
             Throw.IfLitterboxFileSizeExceeds(fileStream.Length, MaxFileSize);
@@ -80,6 +81,7 @@ public LitterboxClient(HttpClient client, IOptions<CatboxOptions> catboxOptions)
     public async Task<string?> UploadImageAsync(TemporaryStreamUploadRequest temporaryStreamUploadRequest, CancellationToken ct = default)
     {
         ArgumentNullException.ThrowIfNull(temporaryStreamUploadRequest?.FileName);
+        ct.ThrowIfCancellationRequested();
 
         if (temporaryStreamUploadRequest!.Stream.CanSeek)
             Throw.IfLitterboxFileSizeExceeds(temporaryStreamUploadRequest.Stream.Length, MaxFileSize);