Fix actions build.

Author: olsgreen

.github/workflows/run_tests.yml

@@ -11,6 +11,11 @@ jobs:
         php: [7.3, 7.4, 8.0]
         laravel: [7.*, 8.*]
         dependency-version: [prefer-stable, prefer-lowest]
+        include:
+          - laravel: 7.*
+            testbench: 5.*
+          - laravel: 8.*
+            testbench: 6.*
 
     name: PHP ${{ matrix.php }}  - Laravel ${{ matrix.laravel }} - Testbench ${{ matrix.testbench }} (${{ matrix.dependency-version }})