Try new testbench

Author: arrilot

.github/workflows/run-tests.yml

@@ -18,7 +18,7 @@ jobs:
         stability: [prefer-lowest, prefer-stable]
         include:
           - laravel: 8.*
-            testbench: ^6.6
+            testbench: ^6.23
 
     name: P${{ matrix.php }} - L${{ matrix.laravel }} - ${{ matrix.stability }} - ${{ matrix.os }}