infra: actions: cache the docker build

.gitea/workflows/gentoo-utils.yml

@@ -3,21 +3,6 @@ name: Gentoo Utils
 on: [push]
 
 jobs:
-  cache:
-    runs-on: ubuntu-latest
-    continue-on-error: true
-    steps:
-      - name: Restore git cache
-        uses: actions/cache@v4
-        with:
-          path: .git
-          key: gitea-repo-${{ gitea.repository }}-${{ gitea.ref }}
-    
-      - name: Checkout repo
-        uses: actions/checkout@v5
-        with:
-          fetch-depth: 0
-
   build-oci-image:
     runs-on: ubuntu-latest
     continue-on-error: true
@@ -39,22 +24,17 @@ jobs:
         id: image-changes
         # build image only if 1. changes are detected or 2. an image for the working branch doesnt exist
         run: |
-          git --no-pager log --oneline -n 10
-          echo "BEFORE = ${{ gitea.event.before }}"
           branch_name="${GITHUB_HEAD_REF:-${GITHUB_REF#refs/heads/}}"
           default_branch_name="${{ gitea.event.repository.default_branch }}"
           image_tag=latest
           comparison_hash="${{ gitea.event.before }}"
 
-          git --no-pager reflog
           if [[ "$branch_name" != "${{ gitea.event.repository.default_branch }}" ]]; then
             image_tag=$branch_name
           fi
           # slugify
           image_tag="$(echo "$image_tag" | sed -E 's/[^a-zA-Z0-9]/-/g')"
 
-
-
           # rebase breaks gitea.event.before, so check to make sure the hash provided exists
           if ! git merge-base --is-ancestor $comparison_hash $branch_name >/dev/null 2>&1; then
             comparison_hash=$(git merge-base origin/$default_branch_name $branch_name)
@@ -95,6 +75,8 @@ jobs:
           push: true
           tags: ${{ vars.REGISTRY_URL }}/${{ gitea.repository }}:${{ steps.image-changes.outputs.image_tag }}
           context: "{{defaultContext}}:.docker"
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
     outputs:
       image_tag: ${{ steps.image-changes.outputs.image_tag }}