Add ActiveModel 6.1 to CI run

Author: ball-hayden

.github/workflows/ci.yml

@@ -18,14 +18,20 @@ jobs:
     strategy:
       matrix:
         ruby: [2.2, 2.3, 2.4, 2.5, 2.6, 2.7]
-        activemodel: [3.2, 4.0, 4.1, 4.2, 5.0, 5.1, 5.2, 6.0]
+        activemodel: [3.2, 4.0, 4.1, 4.2, 5.0, 5.1, 5.2, 6.0, 6.1]
         exclude:
           - ruby: 2.2
             activemodel: 6.0
           - ruby: 2.3
             activemodel: 6.0
           - ruby: 2.4
             activemodel: 6.0
+          - ruby: 2.2
+            activemodel: 6.1
+          - ruby: 2.3
+            activemodel: 6.1
+          - ruby: 2.4
+            activemodel: 6.1
       fail-fast: true
     env:
       ACTIVE_MODEL_VERSION: ${{ matrix.activemodel }}