Dropping support for 32-bit iPhoneOS soon

Since the App Store no longer accepts 32 bit iOS builds, we’d like to remove the support for the platform.
At the same time, we’d like to increase our minimum iOS version to 11.0.

This allows us to remove one architecture from our infrastructure, which will help with our maintenance.

Please let us know if we’ve missed something obvious that should be taken into consideration before moving on with this.

We plan to go ahead with this change soon, hopefully in 1.2.192 if all goes well.