Add Symfony 6.x to the matrix

Author: ste93cry

.github/workflows/tests.yaml

@@ -27,6 +27,7 @@ jobs:
           - 3.4.*
           - 4.4.*
           - 5.*
+          - 6.*
         dependencies:
           - highest
         exclude:
@@ -42,6 +43,9 @@ jobs:
           - php: '7.2'
             symfony-version: 5.*
             dependencies: lowest
+          - php: '7.2'
+            symfony-version: 6.*
+            dependencies: lowest
 
     steps:
       - name: Checkout