fix(ci): lowercase IMAGE_NAME for GHCR compatibility

.github/workflows/docker_release.yml

@@ -31,7 +31,6 @@ concurrency:
 
 env:
   REGISTRY: ghcr.io
-  IMAGE_NAME: ${{ github.repository }}
 
 permissions:
   contents: read
@@ -82,6 +81,7 @@ jobs:
         run: |
           platform=${{ matrix.platform }}
           echo "PLATFORM_PAIR=${platform//\//-}" >> $GITHUB_ENV
+          echo "IMAGE_NAME=${GITHUB_REPOSITORY,,}" >> $GITHUB_ENV
 
       - name: Checkout
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
@@ -135,6 +135,10 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
+      - name: Prepare environment
+        run: |
+          echo "IMAGE_NAME=${GITHUB_REPOSITORY,,}" >> $GITHUB_ENV
+
       - name: Download digests
         uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4.3.0
         with: