[mono][wasm] Fix compilation error on wasm (#54659)

Author: thaystg

src/mono/wasm/debugger/BrowserDebugProxy/MonoSDBHelper.cs

@@ -1446,7 +1446,7 @@ public async Task<JArray> StackFrameGetValues(SessionId sessionId, MethodInfo me
  {
  if (asyncLocal["name"].Value<string>().EndsWith("__this"))
  asyncLocal["name"] = "this";
- else if (asyncLocal["name"].Value<string>().Contains("<"))
+ else if (asyncLocal["name"].Value<string>().Contains('<'))
  asyncLocal["name"] = Regex.Match(asyncLocal["name"].Value<string>(), @"\<([^)]*)\>").Groups[1].Value;
  }
  return asyncLocals;