fix(ci/cd): lock Bundler to version that supports Ruby 2.7

Author: allejo

.github/workflows/ci.yml

@@ -35,10 +35,10 @@ jobs:
 
       - uses: actions/setup-python@v2
         with:
-          python-version: '3.8'
+          python-version: '3.11'
 
       - name: Install bundler
-        run: gem install bundler
+        run: gem install bundler -v 2.4.22
 
       - name: Configure Jekyll
         if: matrix.jekyll-versions != '(GitHub Pages)'