Allow BC check to use current Psalm stack

Author: samdark

composer.json

@@ -42,7 +42,7 @@
         "rector/rector": "^2.5.2",
         "roave/infection-static-analysis-plugin": "^1.18",
         "spatie/phpunit-watcher": "^1.23",
-        "vimeo/psalm": "^4.30|^5.6",
+        "vimeo/psalm": "^4.30|^5.6|^6.0",
         "yiisoft/di": "^1.0",
         "yiisoft/test-support": "^3.0"
     },

psalm.xml

@@ -1,6 +1,7 @@
 <?xml version="1.0"?>
 <psalm
     errorLevel="1"
+    ensureOverrideAttribute="false"
     findUnusedBaselineEntry="true"
     findUnusedCode="false"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"