Task A-6: Switching to step outputs instead of GITHUB_ENV

Refer to details in cleanup issue:
Task A-6: e-mission/e-mission-docs#1082 (comment)

.github/workflows/image_build_push.yml

@@ -18,40 +18,39 @@ jobs:
   build:
     runs-on: ubuntu-latest
 
-    env:
-      DOCKER_TAG_FROM_WORKFLOW_DISPATCH: ${{ github.event.inputs.docker_image_tag }}
-
     steps:
     - uses: actions/checkout@v4
 
-    - name: Set docker image tag from .env file
+    - name: Set docker image tags
+      id: set-tags
       run: |
         set -a; source .env; set +a
-        echo "DOCKER_TAG_FROM_PUSH=${SERVER_IMAGE_TAG}" >> $GITHUB_ENV
+        echo "DOCKER_TAG_FROM_PUSH=${SERVER_IMAGE_TAG}" >> "$GITHUB_OUTPUT"
+        echo "DOCKER_TAG_FROM_WORKFLOW_DISPATCH=${{ github.event.inputs.docker_image_tag }}" >> "$GITHUB_OUTPUT"
 
     - name: Print input docker image tag
       run: |
         echo "Event name: ${{ github.event_name }}"
-        echo "Latest docker image tag (push): ${{ env.DOCKER_TAG_FROM_PUSH }}"
-        echo "Latest docker image tag (workflow_dispatch): ${{ env.DOCKER_TAG_FROM_WORKFLOW_DISPATCH }}"
+        echo "Latest docker image tag (push): ${{ steps.set-tags.outputs.DOCKER_TAG_FROM_PUSH }}"
+        echo "Latest docker image tag (workflow_dispatch): ${{ steps.set-tags.outputs.DOCKER_TAG_FROM_WORKFLOW_DISPATCH }}"
 
     - name: docker login
       run: | # log into docker hub account
         docker login -u $DOCKER_USER -p $DOCKER_PASSWORD
 
     - name: Get current date # get the date of the build
       id: date
-      run: echo "::set-output name=date::$(date +'%Y-%m-%d--%M-%S')"
+      run: echo "date=$(date +'%Y-%m-%d--%M-%S')" >> "$GITHUB_OUTPUT"
 
     - name: Run a one-line script
       run: echo running in repo ${GITHUB_REPOSITORY#*/} branch ${GITHUB_REF##*/} on ${{ steps.date.outputs.date }}
 
     - name: build docker image
       run: |
         if [ "${{ github.event_name }}" == "workflow_dispatch" ]; then
-          SERVER_IMAGE_TAG=$DOCKER_TAG_FROM_WORKFLOW_DISPATCH docker compose -f docker-compose-prod.yml build
+          SERVER_IMAGE_TAG=${{ steps.set-tags.outputs.DOCKER_TAG_FROM_WORKFLOW_DISPATCH }} docker compose -f docker-compose-prod.yml build
         else
-          SERVER_IMAGE_TAG=$DOCKER_TAG_FROM_PUSH docker compose -f docker-compose-prod.yml build
+          SERVER_IMAGE_TAG=${{ steps.set-tags.outputs.DOCKER_TAG_FROM_PUSH }} docker compose -f docker-compose-prod.yml build
         fi
         docker images
 
@@ -67,7 +66,7 @@ jobs:
       run: |
         if [ "${{ github.event_name }}" == "workflow_dispatch" ]; then
           echo "Workflow_dispatch: New server image built and pushed, Updating image tag in .env"
-          echo "SERVER_IMAGE_TAG=$DOCKER_TAG_FROM_WORKFLOW_DISPATCH" > .env
+          echo "SERVER_IMAGE_TAG=${{ steps.set-tags.outputs.DOCKER_TAG_FROM_WORKFLOW_DISPATCH }}" > .env
         else
           echo "Push event: Restoring latest server image tag from .env"
         fi