fix syntax error in workflow

Author: melo936

.github/workflows/main.yml

@@ -14,13 +14,13 @@ jobs:
           channel: 'stable'
           cache: true
 
-    # https://github.com/subosito/flutter-action/issues/278
-    - name: Export pub environment variable
-      run: |
-        if [ "$RUNNER_OS" == "Windows" ]; then
-          echo "PUB_CACHE=$LOCALAPPDATA\\Pub\\Cache" >> $GITHUB_ENV
-        fi
-      shell: bash
+      # https://github.com/subosito/flutter-action/issues/278
+      - name: Export pub environment variable
+        run: |
+          if [ "$RUNNER_OS" == "Windows" ]; then
+            echo "PUB_CACHE=$LOCALAPPDATA\\Pub\\Cache" >> $GITHUB_ENV
+          fi
+        shell: bash
 
       - run: echo "NEW_VERSION=${{ github.ref_name }}" | Out-File -FilePath $env:GITHUB_ENV -Append