{CI} Add --min-severity medium to azdev linter to align with the main repository (#8321)

Author: wangzelin007

scripts/ci/azdev_linter_style.py

@@ -84,7 +84,7 @@ def remove(self):
         self._cmd('azdev extension remove {}'.format(self.extension_name))
 
     def linter(self):
-        self._cmd('azdev linter --include-whl-extensions {}'.format(self.extension_name))
+        self._cmd('azdev linter --include-whl-extensions {} --min-severity medium'.format(self.extension_name))
 
     def style(self):
         self._cmd('azdev style {}'.format(self.extension_name))