Remove PHP from earlier laravel versions test matrix.

Author: olsgreen

.github/workflows/run_tests.yml

@@ -14,18 +14,21 @@ jobs:
         include:
           - laravel: 5.6.*
             testbench: 3.6.*
-            php: 7.1.*
           - laravel: 5.7.*
             testbench: 3.7.*
-            php: 7.1.*
           - laravel: 5.8.*
             testbench: 3.8.*
-            php: 7.1.*
           - laravel: 6.*
             testbench: 4.*
         exclude:
           - laravel: 6.*
             php: 7.1
+          - laravel: 5.6.*
+            php: 8.0
+          - laravel: 5.7.*
+            php: 8.0
+          - laravel: 5.8.*
+            php: 8.0
 
     name: PHP ${{ matrix.php }}  - Laravel ${{ matrix.laravel }} - Testbench ${{ matrix.testbench }} (${{ matrix.dependency-version }})