Update tests.yml

Author: Sergiy Petrov

.github/workflows/tests.yml

@@ -20,7 +20,7 @@ jobs:
  strategy:
  fail-fast: true
  matrix:
- php: [7.2, 7.3, 7.4, 8.0]
+ php: [7.2, 7.3, 7.4, 8.0, 8.1]
 
  name: PHP ${{ matrix.php }}