chore: remove auto git push after version script

Sometimes it was unnecessary making immediate git push after 'npm version', so we should remove it for now.

package.json

@@ -13,7 +13,6 @@
     "prepare": "tsc",
     "build": "tsc",
     "test": "jest",
-    "postversion": "git push && git push --tags",
     "changelog": "github_changelog_generator -u dabakovich -p react-native-controlled-mentions"
   },
   "files": [