GRN2-346: Another attempt at short sha (#2508)

* Short sha

* Another try at short sha

.github/workflows/cd-push.yml

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