React Native / App Store Connect: ITMS-90809: Deprecated API Usage - ios

Question

When I upload my app to the app store, I get a mail from the apple:
ITMS-90809: Deprecated API Usage - New apps that use UIWebView are no longer accepted. Instead, use WKWebView for improved security and reliability. Learn more (https://developer.apple.com/documentation/uikit/uiwebview)
I am unable to understand which is the problem causing library in my code. If anyone would help me in figuring out the problem causing library, I'll be really thankful. When I run: grep -r UIWebView ./* Here is what happens My package.json:
{
"name": "MyApp",
"version": "0.0.1",
"private": true,
"scripts": {
"start": "node node_modules/react-native/local-cli/cli.js start",
"test": "jest"
},
"dependencies": {
"#expo/ex-navigation": "^3.1.0",
"babel-preset-react-native-stage-0": "^1.0.1",
"firebase": "^4.6.2",
"lodash": "^4.17.10",
"moment": "^2.22.1",
"prop-types": "^15.6.0",
"react": "16.0.0",
"react-native": "^0.55.0",
"react-native-datepicker": "^1.7.2",
"react-native-email": "^1.0.2",
"react-native-firebase": "^5.2.3",
"react-native-loading-spinner-overlay": "^0.5.2",
"react-native-step-indicator": "0.0.7",
"react-native-swipe-list-view": "^3.2.5",
"react-native-vector-icons": "^4.4.2",
"react-redux": "^5.0.6",
"redux": "^3.7.2",
"redux-thunk": "^2.2.0"
},
"devDependencies": {
"babel-eslint": "^8.0.3",
"babel-jest": "21.2.0",
"babel-preset-react-native": "4.0.0",
"eslint": "^4.12.1",
"eslint-plugin-react": "^7.5.1",
"eslint-plugin-react-native": "^3.2.0",
"jest": "21.2.1",
"react-native-dotenv": "^0.1.0",
"react-test-renderer": "16.0.0"
},
"jest": {
"preset": "react-native"
},
"rnpm": {
"assets": [
"js/assets/fonts"
]
}
}