CI: use actions/checkout@v4

Author: phw

.github/workflows/test.yml

@@ -23,7 +23,7 @@ jobs:
         ruby-version: ['2.1', '2.6', '2.7', '3.0', '3.1', '3.2', '3.3', '3.4', 'jruby']
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Set up Ruby
     # To automatically get bug fixes and new Ruby versions for ruby/setup-ruby,
     # change this to (see https://github.com/ruby/setup-ruby#versioning):
@@ -51,11 +51,11 @@ jobs:
       packages: write
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Set up Ruby 3.3
       uses: ruby/setup-ruby@v1
       with:
-        ruby-version: 3.3
+        ruby-version: 3.4
 
     # - name: Publish to GPR
     #   run: |