docs: replace @group with Group attribute

Author: kenjis

tests/README.md

@@ -62,8 +62,8 @@ exclude `@DatabaseLive` group. This will make the tests run quite a bit faster.
 ## Groups
 
 Each test class that we are running should belong to at least one
-[@group](https://phpunit.readthedocs.io/en/9.5/annotations.html#group) that is written at class-level
-doc block.
+[Group](https://docs.phpunit.de/en/10.5/attributes.html#group) attribute that is
+written at class-level doc block.
 
 The available groups to use are: