Do not fail on puppet 7 / Ruby 2.7

Author: ahayworth

.github/workflows/main.yml

@@ -93,7 +93,12 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby-version: ["2.5", "2.6", "2.7", "3.0"]
+        ruby-version: ["2.5", "2.6"]
+        experimental: [false]
+      include:
+        - { ruby-version: "2.7", experimental: true }
+        - { ruby-version: "3.0", experimental: true }
+    continue-on-error: ${{ matrix.experimental }}
     steps:
       - name: Checkout code
         uses: actions/checkout@v1