[String] move symfony/translation-contracts to require-dev

Author: nicolas-grekas

composer.json

@@ -19,12 +19,12 @@
         "php": "^7.2.5",
         "symfony/polyfill-intl-grapheme": "~1.0",
         "symfony/polyfill-intl-normalizer": "~1.0",
-        "symfony/polyfill-mbstring": "~1.0",
-        "symfony/translation-contracts": "^1.1|^2"
+        "symfony/polyfill-mbstring": "~1.0"
     },
     "require-dev": {
         "symfony/error-handler": "^4.4|^5.0",
         "symfony/http-client": "^4.4|^5.0",
+        "symfony/translation-contracts": "^1.1|^2",
         "symfony/var-exporter": "^4.4|^5.0"
     },
     "autoload": {