composer: used Tester 2

dg · dg · commit 4fb88603cc7e · 2016-05-17T17:49:16.000+02:00
diff --git a/composer.json b/composer.json
@@ -19,7 +19,7 @@
 	},
 	"require-dev": {
 		"nette/di": "^2.3",
-		"nette/tester": "^1.4",
+		"nette/tester": "~2.0",
 		"tracy/tracy": "^2.3"
 	},
 	"conflict": {
