Upgrade GH workflow iOS runner to macOS 14 arm64

- Standard GH macos-14 (arm64) free/unlimited for public
- Fix: #1776
  - Arch: Intel (x86_64) -> arm64
  - CPU: 4-core (Intel) -> 3-core (M1)
  - RAM: 14 GB -> 7 GB
  - macOS: 13->14
  - Darwin: 22->23
  - XcodeCLI: 14->16
  - SSD: 14GB
- Remove old macOS 13 image spec docs

Author: leotm

.github/workflows/ios.yml

@@ -9,10 +9,7 @@ on:
 jobs:
   build-ios:
 
-    runs-on: macos-13
-
-    # ruby: 2.7.6, 3.0.4, 3.1.2 (../.ruby-version: 2.7.5)
-    # CocoaPods: 1.11.3
+    runs-on: macos-14
 
     steps: