Use build arg in docker action to correctly pass git commit SHA (#3940)

* use env variables through docker args

* remove quotes

* use an output instead

* try that again

* write the variables to .env

* rm unused

* use short sha

* remove test branch

.github/workflows/build-and-push-bskyweb-aws.yaml

@@ -43,6 +43,10 @@ jobs:
           tags: |
             type=sha,enable=true,priority=100,prefix=,suffix=,format=long
 
+      - name: Set outputs
+        id: vars
+        run: echo "sha_short=$(git rev-parse --short HEAD)" >> $GITHUB_OUTPUT
+
       - name: Build and push Docker image
         id: build-and-push
         uses: docker/build-push-action@v4
@@ -54,6 +58,5 @@ jobs:
           labels: ${{ steps.meta.outputs.labels }}
           cache-from: type=gha
           cache-to: type=gha,mode=max
-        env:
-          EXPO_PUBLIC_BUNDLE_IDENTIFIER: $(git rev-parse --short HEAD)
-          EXPO_PUBLIC_BUNDLE_DATE: $(date -u +"%y%m%d%H")
+          build-args: |
+            EXPO_PUBLIC_BUNDLE_IDENTIFIER=${{ steps.vars.outputs.sha_short }}