I had recently solved this problem by uninstalling the higher version of JDK and installing JDK 8. After installing the JDK you need to give the path. Then you need to open command prompt in "C:\Users\Milan Adhikari\AppData\Local\Android\Sdk\tools" and run "sdkmanager --update" which will update your sdk and then you need to run "flutter doctor --android-licenses" in cmd and accept all the licenses.
Now your problem should be solved.