Semver tags for Docker images (#720)

The main Gitea docker image is already distributed with proper semver tags, such that users can pin to e.g. the minor version and still pull in patch releases.  This is something that has been lacking on the act runner images.

This PR expands the docker image tag versioning strategy such that when `v0.2.13` is released the following image tags are produced:

Basic:
 - `0`
 - `0.2`
 - `0.2.13`
 - `latest`

DinD:
 - `0-dind`
 - `0.2-dind`
 - `0.2.13-dind`
 - `latest-dind`

DinD-Rootless:
 - `0-dind-rootless`
 - `0.2-dind-rootless`
 - `0.2.13-dind-rootless`
 - `latest-dind-rootless`

To verify the `docker/metadata-action` produces the expected results in a Gitea workflow environment I've executed a release workflow. Results can be seen in [this run](https://gitea.com/RoboMagus/gitea_act_runner/actions/runs/14). (Note though that as the repository name of my fork changed from `act_runner` to `gitea_act_runner` this is reflected in the produced docker tags in this test run!)

---------

Co-authored-by: RoboMagus <68224306+RoboMagus@users.noreply.github.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@noreply.gitea.com>
Reviewed-on: https://gitea.com/gitea/act_runner/pulls/720
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: RoboMagus <robomagus@noreply.gitea.com>
Co-committed-by: RoboMagus <robomagus@noreply.gitea.com>

.gitea/workflows/release-tag.yml

@@ -39,6 +39,15 @@ jobs:
           GPG_FINGERPRINT: ${{ steps.import_gpg.outputs.fingerprint }}
   release-image:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        variant:
+          - target: basic
+            tag_suffix: ""
+          - target: dind
+            tag_suffix: "-dind"
+          - target: dind-rootless
+            tag_suffix: "-dind-rootless"
     container:
       image: catthehacker/ubuntu:act-latest
     env:
@@ -62,50 +71,33 @@ jobs:
           username: ${{ secrets.DOCKER_USERNAME }}
           password: ${{ secrets.DOCKER_PASSWORD }}
 
-      - name: Get Meta
+      - name: Repo Meta
-        id: meta
+        id: repo_meta
         run: |
           echo REPO_NAME=$(echo ${GITHUB_REPOSITORY} | awk -F"/" '{print $2}') >> $GITHUB_OUTPUT
-          echo REPO_VERSION=${GITHUB_REF_NAME#v} >> $GITHUB_OUTPUT
+
+      - name: "Docker meta"
+        id: docker_meta
+        uses: https://github.com/docker/metadata-action@v5
+        with:
+          images: |
+            ${{ env.DOCKER_ORG }}/${{ steps.repo_meta.outputs.REPO_NAME }}
+          tags: |
+            type=semver,pattern={{major}}.{{minor}}.{{patch}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}}
+          flavor: |
+            latest=true
+            suffix=${{ matrix.variant.tag_suffix }},onlatest=true
 
       - name: Build and push
         uses: docker/build-push-action@v6
         with:
           context: .
           file: ./Dockerfile
-          target: basic
+          target: ${{ matrix.variant.target }}
           platforms: |
             linux/amd64
             linux/arm64
           push: true
-          tags: |
+          tags: ${{ steps.docker_meta.outputs.tags }}
-            ${{ env.DOCKER_ORG }}/${{ steps.meta.outputs.REPO_NAME }}:${{ steps.meta.outputs.REPO_VERSION }}
-            ${{ env.DOCKER_ORG }}/${{ steps.meta.outputs.REPO_NAME }}:${{ env.DOCKER_LATEST }}
-
-      - name: Build and push dind
-        uses: docker/build-push-action@v6
-        with:
-          context: .
-          file: ./Dockerfile
-          target: dind
-          platforms: |
-            linux/amd64
-            linux/arm64
-          push: true
-          tags: |
-            ${{ env.DOCKER_ORG }}/${{ steps.meta.outputs.REPO_NAME }}:${{ steps.meta.outputs.REPO_VERSION }}-dind
-            ${{ env.DOCKER_ORG }}/${{ steps.meta.outputs.REPO_NAME }}:${{ env.DOCKER_LATEST }}-dind
-
-      - name: Build and push dind-rootless
-        uses: docker/build-push-action@v6
-        with:
-          context: .
-          file: ./Dockerfile
-          target: dind-rootless
-          platforms: |
-            linux/amd64
-            linux/arm64
-          push: true
-          tags: |
-            ${{ env.DOCKER_ORG }}/${{ steps.meta.outputs.REPO_NAME }}:${{ steps.meta.outputs.REPO_VERSION }}-dind-rootless
-            ${{ env.DOCKER_ORG }}/${{ steps.meta.outputs.REPO_NAME }}:${{ env.DOCKER_LATEST }}-dind-rootless