Authorize is picking the default browser instead of browser specified with iosCustomBrowser

## Issue
Hello !

We are encountering an issue when using authorize function.

We defined our default browser to be Chrome on our iPhones.
We defined the `iosCustomBrowser` authorization config field to be `safari`.

When we launch the authorization flow, even if `safari` is specified, the authorization session is opened through Chrome.
When setting back Safari as our default browser, the authorization session is correctly opened through Safari.

Thanks in advance for your responses !
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## Environment

* **Your Identity Provider**: `other`
* **Platform that you're experiencing the issue on**: `iOS`
* **Your `react-native` Version**: `0.73.3`
* **Your `react-native-app-auth` Version**: `7.1.0 and 8.0.1`
* **Are you using Expo?**: `Yes`