Short sha (#2507)

.github/workflows/cd-push.yml

@@ -21,6 +21,9 @@ jobs:
           username: ${{ secrets.DOCKER_USERNAME }}
           password: ${{ secrets.DOCKER_PASSWORD }}
 
+      - name: Step for Short SHA
+        run: echo "::set-output name=sha_short::$(git rev-parse --short HEAD)"
+
       - name: Build and Push latest
         uses: docker/build-push-action@v2
         with:
@@ -28,4 +31,4 @@ jobs:
           tags: |
             bigbluebutton/greenlight:master
             bigbluebutton/greenlight:latest
-          build-args: version_code=${{ GITHUB_SHA::8 }}
+          build-args: version_code=${{ steps.vars.outputs.sha_short  }}