Run CI on 8.1

.github/workflows/run-tests.yml

@@ -13,15 +13,16 @@ jobs:
         php:
         - '7.4'
         - '8.0'
+        - '8.1'
         deps:
         - stable
         - lowest
         - dingo
         exclude:
-          - php: '8.0'
-            deps: dingo
-          - php: '8.0'
-            deps: lowest
+          - {php: '8.0', deps: dingo}
+          - {php: '8.0', deps: lowest}
+          - {php: '8.1', deps: dingo}
+          - {php: '8.1', deps: lowest}
 
     name: Tests (PHP ${{ matrix.php }} - ${{ matrix.deps }})