deploy: work around the grayed out "Enforce HTTPS" checkbox

We do want to enforce HTTPS. And we kind of do, but not "kind of" enough
for GitHub's UI at https://github.com/git/git-scm.com/settings/pages to
allow us to check the box called "Enforce HTTPS".

The helpful comment next to the grayed out box says:

  [ ] **Enforce HTTPS** --- Unavailable for your site because your
  domain is not properly configured to support HTTPS
  ([`git-scm.com`](http://git-scm.com/)) --- [Troubleshooting custom
  domains](https://docs.github.com/articles/troubleshooting-custom-domains/#https-errors)

  HTTPS provides a layer of encryption that prevents others from
  snooping on or tampering with traffic to your site.
  When HTTPS is enforced, your site will only be served over HTTPS.
  [Learn more about securing your GitHub Pages site with
  HTTPS](https://docs.github.com/pages/getting-started-with-github-pages/securing-your-github-pages-site-with-https).

As discussed in #1953, it would
appear to be outside our capabilities to fix this properly, therefore we
are unfortunately stuck with hard-coding a work-around: Manually
override the http:// URL produced by `actions/configure-pages` with the
equivalent https:// one.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

.github/actions/deploy-to-github-pages/action.yml

@@ -47,7 +47,9 @@ runs:
         set -x &&
         echo "HUGO_VERSION=$(sed -n 's/^ *hugo_version: *//p' <hugo.yml)" >>$GITHUB_ENV
         echo "PAGEFIND_VERSION=$(sed -n 's/^ *pagefind_version: *//p' <hugo.yml)" >>$GITHUB_ENV
-        echo "BASE_URL=${{ steps.pages.outputs.base_url }}" >>$GITHUB_ENV
+        BASE_URL=${{ steps.pages.outputs.base_url }}
+        test http://git-scm.com != "$BASE_URL" || BASE_URL="https://${BASE_URL#http://}"
+        echo "BASE_URL=$BASE_URL" >>$GITHUB_ENV
 
     - name: install Hugo ${{ env.HUGO_VERSION }}
       shell: bash