CI: build container when the version is a clean tag

.forgejo/workflows/build.yaml

@@ -1,25 +1,49 @@
 on:
+  push:
   workflow_dispatch:
+    inputs:
+      build:
+        description: "Build container"
+        required: true
+        default: true
+        type: boolean
 
 jobs:
   build:
     runs-on: container
     steps:
       - uses: actions/checkout@v4
-
-      - name: Git unshallow - get all history from Git to get the tag for the computation of the version
-        run: git pull --unshallow
+        with:
+          fetch-depth: 0
 
       - name: Get the version from git
         id: version
         run: echo "version=$(git describe --dirty --tags)" >> $GITHUB_OUTPUT
 
+      - name: Check if the container should be built
+        id: builder
+        env:
+          RUN: ${{ toJSON(inputs.build || !contains(steps.version.outputs.version, '-')) }}
+        run: |
+          echo "run=$RUN" >> $GITHUB_OUTPUT
+          echo "Run build: $RUN"
+
+      - name: Info - version and if the image container should be built
+        env:
+          VERSION: ${{ steps.version.outputs.version }}
+          RUN: ${{ steps.builder.outputs.run }}
+          FORCE: ${{ toJSON(inputs.build) }}
+        run: |
+          echo "Version $VERSION, force (manual input): $FORCE, run the build: $RUN"
+
       - name: Workaround for bug of podman-login
+        if: fromJSON(steps.builder.outputs.run)
         run: |
           mkdir -p $HOME/.docker
           echo "{ \"auths\": {} }" > $HOME/.docker/config.json
 
       - name: Log in to the container registry (with another workaround)
+        if: fromJSON(steps.builder.outputs.run)
         uses: actions/podman-login@v1
         with:
           registry: ${{ vars.REGISTRY }}
@@ -28,6 +52,7 @@ jobs:
           auth_file_path: /tmp/auth.json
 
       - name: Build the container image
+        if: fromJSON(steps.builder.outputs.run)
         uses: actions/buildah-build@v1
         with:
           image: treetrail-backend
@@ -38,6 +63,7 @@ jobs:
             ./Containerfile
 
       - name: Push the image to the registry
+        if: fromJSON(steps.builder.outputs.run)
         uses: actions/push-to-registry@v2
         with:
           registry: "docker://${{ vars.REGISTRY }}"