Fix GitHub Actions failures by downgrading Ruby from 4.0 to 3.3 (#86)

Renovate PR #80 upgraded ruby-version to 4.0.0, but the ffi gem (1.17.2)
required by cocoapods only supports Ruby < 3.5. This caused bundle install
to fail on every scheduled run since January 20.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: d-date

.github/workflows/build-mlkit.yml

@@ -26,7 +26,7 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: '4.0.1'
+          ruby-version: '3.3'
           bundler-cache: true
 
       - name: Set up Xcode

.github/workflows/check-mlkit-updates.yml

@@ -26,7 +26,7 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: '4.0.1'
+          ruby-version: '3.3'
           bundler-cache: true
 
       - name: Check for MLKit updates