Update github ci

Author: chrysanthos

.github/workflows/tests.yml

@@ -9,7 +9,7 @@ jobs:
       fail-fast: true
       matrix:
         php: [7.4, 8.0, 8.1]
-        laravel: [6.*, 7.*, 8.*]
+        laravel: [7.*, 8.*]
         include:
           - laravel: 7.*
             testbench: 5.*