[ASP.NET Core] Fix network.protocol.version

src/OpenTelemetry.Instrumentation.AspNetCore/Implementation/HttpTagHelper.cs

@@ -31,10 +31,10 @@ public static string GetFlavorTagValueFromProtocol(string protocol)
         switch (protocol)
         {
             case "HTTP/2":
-                return "2.0";
+                return "2";
 
             case "HTTP/3":
-                return "3.0";
+                return "3";
 
             case "HTTP/1.1":
                 return "1.1";