composer: Update phpstan (#7)

To support PHP 8

Author: jtojnar

composer.json

@@ -21,8 +21,8 @@
 		"nette/bootstrap": "~3.0",
 		"nette/di": "~3.0",
 		"nette/robot-loader": "~3.0",
-		"phpstan/phpstan-nette": "0.11",
-		"phpstan/phpstan-shim": "0.11.5",
+		"phpstan/phpstan-nette": "0.12.21",
+		"phpstan/phpstan": "0.12.99",
 		"tracy/tracy": "~2.5"
 	},
 	"extra": {