fix: require Psalm ^5.16 for MissingOverrideAttribute support

The MissingOverrideAttribute issue type was added in Psalm 5.16.0.
Older versions fail to parse psalm.xml when this issue is referenced
in issueHandlers, causing CI failures with prefer-lowest.

Author: cryptiklemur

composer.json

@@ -18,7 +18,7 @@
 		"symfony/options-resolver": "^5.4 || ^6.0 || ^7.0 || ^8.0",
 		"symfony/yaml": "^5.0 || ^6.0 || ^7.0 || ^8.0",
 		"symplify/easy-coding-standard": "^12",
-		"vimeo/psalm": "^5.0 || ^6.0"
+		"vimeo/psalm": "^5.16 || ^6.0"
 	},
 	"license":     "MIT",
 	"authors":     [