fix: add react-native.config.js to npm package (#1611)

## Description

Autolinking was added with #1585 and it added `react-native.config.js`
file with codegen configuration, **but** it did not add this file to npm
include list causing its absence in final released package...

Fixes #1608

## Changes

Added `react-native.config.js` to npm file list in main `package.json`


## Test code and steps to reproduce

See #1608 for reproductions.

## Checklist

- [x] Ensured that CI passes

package.json

@@ -38,6 +38,7 @@
     "ios/",
     "windows/",
     "RNScreens.podspec",
+    "react-native.config.js",
     "README.md",
     "!**/__tests__",
     "!android/src/main/java/com/swmansion/rnscreens/LifecycleHelper.kt"