change PendingIntent to FLAG_IMMUTABLE

[dagovalsusa]

change the pending intent from FLAG_UPDATE_CURRENT to FLAG_IMMUTABLE.
FLAG_UPDATE_CURRENT cause a crash/error on Android 12

Strongly consider using FLAG_IMMUTABLE, only use FLAG_MUTABLE if some functionality depends on the PendingIntent being mutable, e.g. if it needs to be used with inline replies or bubbles., null, java.lang.IllegalArgumentException: app.aworld: Targeting S+ (version 31 and above) requires that one of FLAG_IMMUTABLE or FLAG_MUTABLE be specified when creating a PendingIntent.

I've tested on simulator with Android 12

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[samry]

FWIW: I was running into the same issues/errors as described in the PR when targeting SDK version 31, and this commit fixes it.

[ryanheise]

@samry can you take a look at #836 where this issue is discussed? I would like to get a fix for this released, but #836 is where the important discussions have taken place, and I can't merge it until people can test the work being done there.

[ryanheise]

I am closing this since the fix/android_intent_flags branch already exists and would suggest people continue the discussion at #836 .