Don't use upload-pages-artifact

In upload-pages-artifact@v4 the maintainers have made the curious
decision to omit hidden files (files whose names begin with ".") from
the site that gets deployed to GitHub Pages and to provide no way to
include a hidden file (at least "for now"), even though static sites may
of course want to include files whose names begin with "."

https://github.com/actions/upload-pages-artifact/pull/102

Work around this in by creating the "artifact" (tar file) ourselves and
uploading it using the upload-artifact action, as suggested in the
upload-pages-artifact PR linked above.

.github/workflows/github_pages.yml

@@ -85,10 +85,28 @@ jobs:
           chmod -c -R +rX "${{ inputs.output-path }}" | while read line; do
             echo "::warning title=Invalid file permissions automatically fixed::$line"
           done
+      - name: Archive artifact
+        shell: sh
+        run: |
+          echo "::group::Archive artifact"
+          tar \
+            --dereference \
+            --hard-dereference \
+            --directory "$OUTPUT_PATH" \
+            -cvf "$RUNNER_TEMP/artifact.tar" \
+            --exclude=.git \
+            --exclude=.github \
+            .
+          echo "::endgroup::"
+        env:
+          OUTPUT_PATH: ${{ inputs.output-path }}
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
-          path: ${{ inputs.output-path }}
+          name: github-pages
+          path: ${{ runner.temp }}/artifact.tar
+          retention-days: 1
+          if-no-files-found: error
   deploy:
     concurrency:
       group: "pages"