Update android.yml

Author: muzahidul-opti

.github/workflows/android.yml

@@ -40,12 +40,10 @@ jobs:
         ref: 'master'
 
     - name: set SDK Branch if PR
-      env:  
-        HEAD_REF: ${{ github.head_ref }}
       if: ${{ github.event_name == 'pull_request' }}
       run: |
-        echo "SDK_BRANCH=${{ env.HEAD_REF }}" >> $GITHUB_ENV
-        echo "TRAVIS_BRANCH=${{ env.HEAD_REF }}" >> $GITHUB_ENV
+        echo "SDK_BRANCH=${{ github.head_ref }}" >> $GITHUB_ENV
+        echo "TRAVIS_BRANCH=${{ github.head_ref }}" >> $GITHUB_ENV
     - name: set SDK Branch if not pull request
       if: ${{ github.event_name != 'pull_request' }}
       run: |