Update concurrent-ruby requirement from < 1.3.4 to < 1.3.8 in /example

Updates the requirements on [concurrent-ruby](https://github.com/ruby-concurrency/concurrent-ruby) to permit the latest version.
- [Release notes](https://github.com/ruby-concurrency/concurrent-ruby/releases)
- [Changelog](https://github.com/ruby-concurrency/concurrent-ruby/blob/master/CHANGELOG.md)
- [Commits](https://github.com/ruby-concurrency/concurrent-ruby/compare/v0.0.1...v1.3.7)

---
updated-dependencies:
- dependency-name: concurrent-ruby
  dependency-version: 1.3.7
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/android-build.yml

@@ -39,7 +39,7 @@ jobs:
     name: Build Android Example App
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v7
+      - uses: actions/checkout@v4
       - uses: oven-sh/setup-bun@v2
 
       - name: Install dependencies (bun)

.github/workflows/ios-build.yml

@@ -50,7 +50,7 @@ jobs:
     name: Build iOS Example App
     runs-on: macOS-15
     steps:
-      - uses: actions/checkout@v7
+      - uses: actions/checkout@v4
       - uses: oven-sh/setup-bun@v2
       - name: Setup Xcode
         uses: maxim-lobanov/setup-xcode@v1

.github/workflows/release.yml

@@ -21,7 +21,7 @@ jobs:
       id-token: write
     steps:
       - name: Checkout
-        uses: actions/checkout@v7
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
       - name: Setup Bun.js

example/Gemfile

@@ -7,7 +7,7 @@ ruby ">= 2.6.10"
 gem 'cocoapods', '>= 1.13', '!= 1.15.0', '!= 1.15.1'
 gem 'activesupport', '>= 6.1.7.5', '!= 7.1.0'
 gem 'xcodeproj', '< 1.26.0'
-gem 'concurrent-ruby', '< 1.3.4'
+gem 'concurrent-ruby', '< 1.3.8'
 
 # Ruby 3.4.0 has removed some libraries from the standard library.
 gem 'bigdecimal'