Automate upload of release archives

(Just a dry run test for now)

Add a GHA workflow which triggers whenever a versioned tag is pushed to
automatically draft a release using
https://github.com/softprops/action-gh-release. Git archives of the repo
and all of its submodules are generated using
https://github.com/Kentzo/git-archive-all and uploaded as release
artifacts (both .zip & .tar.gz).

This is a workaround for
dear-github/dear-github#214. The archives
generated by GitHub on each release do not contain submodules.

.github/workflows/cd.yml

@@ -0,0 +1,25 @@
+name: CD
+
+on:
+  push:
+    # tags:
+    #   - "v*.*.*"
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with: { fetch-depth: 0, submodules: true }
+      - run: |
+          pipx run git-archive-all snaphu-py-${{ github.ref_name }}.zip
+          unzip -l snaphu-py-${{ github.ref_name }}.zip
+      - run: |
+          pipx run git-archive-all snaphu-py-${{ github.ref_name }}.tar.gz
+          tar -ztvf snaphu-py-${{ github.ref_name }}.tar.gz
+      # - uses: softprops/action-gh-release@v1
+      #   with:
+      #     files: |
+      #       snaphu-py-${{ github.ref_name }}.zip
+      #       snaphu-py-${{ github.ref_name }}.tar.gz
+      #     generate_release_notes: true