Revert "Increase default language version"

This reverts commit d66da69.

Author: GrahamTheCoder

Web/ConverterController.cs

@@ -60,7 +60,7 @@ private int GetDefaultVersionForLanguage(string language)
             if (language == null)
                 throw new ArgumentNullException(nameof(language));
             if (language.StartsWith("cs", StringComparison.OrdinalIgnoreCase))
-                return 8;
+                return 6;
             if (language.StartsWith("vb", StringComparison.OrdinalIgnoreCase))
                 return 14;
             throw new ArgumentException($"{language} not supported!");