Added "gem install bundler" because it does not come with Ruby by default

.gitea/workflows/compile.yml

@@ -9,10 +9,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v3
 
-      - name: Install Ruby
+      - name: Install Ruby and Bundler
         run: |
           apt-get update
           apt-get install -y ruby-full
+          gem install bundler
 
       - name: Install dependencies
         run: bundle install