Upgrade XCode image to 11.4.0

.circleci/config.yml

@@ -221,7 +221,7 @@ commands:
 jobs:
   Check Swift formatting:
     macos:
-      xcode: "11.3.1"
+      xcode: "11.4.0"
     steps:
       - checkout
       - run: brew install swiftlint swiftformat
@@ -291,7 +291,7 @@ jobs:
       - save-sccache-cache
   iOS build and test:
     macos:
-      xcode: "11.3.1"
+      xcode: "11.4.0"
     steps:
       - install-rust
       - setup-rust-toolchain
@@ -369,7 +369,7 @@ jobs:
             - MozillaAppServices.framework.zip
   Carthage release:
     macos:
-      xcode: "11.3.1"
+      xcode: "11.4.0"
     steps:
       - checkout
       - attach_workspace:

CHANGES_UNRELEASED.md

@@ -4,6 +4,12 @@
 
 [Full Changelog](https://github.com/mozilla/application-services/compare/v0.55.0...master)
 
+## General
+
+### What's changed
+
+- iOS: Xcode version changed to 11.4.0 from 11.3.1.
+
 ## Logins
 
 ### ⚠️ Breaking changes ⚠️