Add support for Laravel 13

- Allow illuminate/contracts ^13.0
- Allow orchestra/testbench ^11.0 and Pest 4 (with plugins) for dev
- Add Laravel 13 to the CI test matrix
- Update requirements in README

.github/workflows/run-tests.yml

@@ -18,7 +18,7 @@ jobs:
       matrix:
         os: [ubuntu-latest]
         php: [8.3, 8.4]
-        laravel: [11.*, 12.*]
+        laravel: [11.*, 12.*, 13.*]
         stability: [prefer-lowest, prefer-stable]
         include:
           - laravel: 11.*
@@ -37,6 +37,14 @@ jobs:
             php: 8.4
             testbench: 10.*
             carbon: ^3.8.4
+          - laravel: 13.*
+            php: 8.3
+            testbench: 11.*
+            carbon: ^3.8.4
+          - laravel: 13.*
+            php: 8.4
+            testbench: 11.*
+            carbon: ^3.8.4
 
     name: P${{ matrix.php }} - L${{ matrix.laravel }} - ${{ matrix.stability }} - ${{ matrix.os }}