WIP: CI: Add new workflow to create all casks [skip-ci]

Now we can create the casks of some specific release ('latest' in this
case) at will, based purely on the artifact files and on nothing in the
repo. We do not even need to fetch the repo.

Signed-off-by: Fini Jastrow <ulf.fini.jastrow@desy.de>

.github/workflows/casks.yml

@@ -0,0 +1,35 @@
+name: Create Casks PR
+
+on:
+  workflow_dispatch:
+
+jobs:
+  create-casks:
+    name: Create casks
+    runs-on: ubuntu-latest
+    steps:
+      - name: Fetch stuff (no checkout)
+        uses: Bhacaz/checkout-files@v2
+        with:
+          files: bin/scripts/lib/fonts.json bin/scripts/fetch-archives.sh bin/scripts/generate-casks.sh
+          branch: ${{ github.head_ref || github.ref_name }}
+      - name: Fetch release artifacts
+        run: |
+          cd bin/scripts
+          chmod u+x *
+          ./fetch-archives.sh latest
+      - name: Determine release tag
+        id: releasetag
+        run: |
+          TAG=$(ls archives/_Release* | head -n 1 | sed 's/.*_Release_//')
+          echo "Release has tag ${TAG}"
+          echo "tag=${TAG}" >> $GITHUB_OUTPUT
+      - name: Create all casks
+        run: |
+          cd bin/scripts
+          ./generate-casks.sh --setversion ${{ steps.releasetag.outputs.tag }}
+      - name: Upload casks as artifacts
+        uses: actions/upload-artifact@v2
+        with:
+          name: casks
+          path: casks