Update coverage.yml

Author: wangzelin007

.github/workflows/coverage.yml

@@ -66,8 +66,10 @@ jobs:
         set -ev
         cd ../azure-cli
         git checkout f205ee4
+        git switch -c f205ee4
         cd ../azure-cli-extensions
         git checkout fc5ae18
+        git switch -c fc5ae18
 
     - name: Set Up Python Environment
       run: |