Bump iOS target version to 13.0 for capacitor 4 and add prepare script.

[davidhulick]

• Updated the deployment targets throughout the plugin to iOS 13.0 to fall in line with the default deployment targets for Capacitor 4.
• Added prepare script to package.json to allow installing the module from github

[mineminemine]

Is there no update on this?

[opindia123]

Is there any progress for above ios changes?

[jcesarmobile]

this was already done in https://github.com/capacitor-community/fcm/pull/122 with all other Capacitor 4 required changes