Update Apple Toolchain Used in GitHub Actions (#1876)

Summary:
We were using `macos-13`, back at a time where `macos-latest` was too out of date. Let's go back to `macos-latest`, and latest stable XCode.

Pull Request resolved: #1876

Test Plan: The workflows now pass in PR

Reviewed By: cipolleschi, cortinico

Differential Revision: D93552138

Pulled By: NickGerleman

fbshipit-source-id: 4e825f25d96b88d50187b04801aac3fbd1090fb7

Author: NickGerleman

.github/actions/setup-apple/action.yml

@@ -10,4 +10,4 @@ runs:
 
     - uses: maxim-lobanov/setup-xcode@v1
       with:
-        xcode-version: 14.3.1
+        xcode-version: 26.2

.github/workflows/publish-cocoapods-release.yml

@@ -9,7 +9,7 @@ on:
 jobs:
   publish:
     name: Publish to CocoaPods trunk
-    runs-on: macos-13
+    runs-on: macos-latest
 
     steps:
       - uses: actions/checkout@v3

.github/workflows/validate-apple.yml

@@ -11,7 +11,7 @@ on:
 jobs:
   lint-pods:
     name: Build [CocoaPods]
-    runs-on: macos-13
+    runs-on: macos-latest
 
     steps:
       - uses: actions/checkout@v3
@@ -24,7 +24,7 @@ jobs:
 
   test:
     name: Build [SwiftPM]
-    runs-on: macos-13
+    runs-on: macos-latest
 
     steps:
       - uses: actions/checkout@v3