Disable iOS builds

I can't seem to get builds working using Dart FFI because of codesigning
issues... Since I'll anyway never be able to publish the app on the
AppStore, drop the build for now.

README.md

@@ -1,7 +1,6 @@
 # Flouze, an app to keep track of expenses among friends
 
 [![CircleCI](https://circleci.com/gh/abustany/flouze.svg?style=svg)](https://circleci.com/gh/abustany/flouze)
-[![Build Status](https://travis-ci.com/abustany/flouze.svg?branch=master)](https://travis-ci.com/abustany/flouze)
 
 [Download prebuilt binaries here!](https://flouze.bustany.org)
 
@@ -41,11 +40,10 @@ The features currently being developed include:
 
 ## Compatibility
 
-Rust and Flutter allow targeting both Android and iOS as mobile platforms.  I
-currently only develop for Android, and try to make things work for iOS once
-every now and then, but given I have no Apple Developer Account this does not
-mean much. There's also a very basic CLI tool for interacting with Flouze
-accounts, that one should work on all desktop platforms.
+Rust and Flutter theoretically allow targeting both Android and iOS as mobile
+platforms. I currently only develop for Android. There's also a very basic CLI
+tool for interacting with Flouze accounts, that one should work on all desktop
+platforms.
 
 ## Development