Update README.md

Updated examples to use checkout v5

Author: jwillemsen

README.md

@@ -76,7 +76,7 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v5
     - uses: ruby/setup-ruby@v1
       with:
         ruby-version: '3.4' # Not needed with a .ruby-version, .tool-versions or mise.toml
@@ -101,7 +101,7 @@ jobs:
         ruby: ['2.7', '3.0', '3.1', '3.2', '3.3', '3.4', head, jruby, jruby-head, truffleruby, truffleruby-head]
     runs-on: ${{ matrix.os }}
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v5
     - uses: ruby/setup-ruby@v1
       with:
         ruby-version: ${{ matrix.ruby }}
@@ -124,7 +124,7 @@ jobs:
     env: # $BUNDLE_GEMFILE must be set at the job level, so it is set for all steps
       BUNDLE_GEMFILE: ${{ github.workspace }}/gemfiles/${{ matrix.gemfile }}.gemfile
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: '3.4'