feat: add step to restore debug keystore in Android build workflow

.gitea/workflows/android.yaml

@@ -65,6 +65,11 @@ jobs:
           echo "ANDROID_HOME=$ANDROID_HOME" >> $GITHUB_ENV
           echo "ANDROID_SDK_ROOT=$ANDROID_HOME" >> $GITHUB_ENV
 
+      - name: Restore debug keystore
+        run: |
+          mkdir -p ~/.android
+          echo "${{ secrets.KEYSTORE_BASE64 }}" | base64 -d > ~/.android/debug.keystore
+
       - name: Create google-services.json
         run: echo "${{ secrets.GOOGLE_SERVICES_JSON }}" | base64 -d > app/google-services.json