composer: Install stable nextras/forms-rendering

We needed the dev before nextras/forms-rendering@8776b68 was released.

 - nextras/forms-rendering updated from dev-master@ec07cdf to v2.0.0 major
   See changes: nextras/forms-rendering@ec07cdf...v2.0.0
   Release notes: https://github.com/nextras/forms-rendering/releases/tag/v2.0.0

Author: jtojnar

composer.json

@@ -32,7 +32,7 @@
 		"nette/security": "~3.0",
 		"nette/utils": "~4.0",
 		"nextras/form-components": "^2.0",
-		"nextras/forms-rendering": "@dev",
+		"nextras/forms-rendering": "^2.0",
 		"nextras/orm": "^5.0",
 		"pelago/emogrifier": "^7.0",
 		"rikudou/iban": "^1.3",