Update checkout GHA to avoid Node16 deprecation warnings (#239)

Summary:
This is a very basic PR I know. But it cleans up the deprecation warnings so I thought I'd add it.

Pull Request resolved: #239

Test Plan:
Imported from GitHub, without a `Test Plan:` line.

Checked https://github.com/facebook/chef-cookbooks/pull/239/checks, deprecation notices are gone

Differential Revision: D57752486

fbshipit-source-id: aa4accc12e6dcbab47e6a1637502eec5f17f508e

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Setup Ruby
       uses: ruby/setup-ruby@v1
       with:
@@ -37,7 +37,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Install Chef
       uses: actionshub/chef-install@2.0.4
       with:
@@ -55,6 +55,6 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Run Shellcheck
         uses: ludeeus/action-shellcheck@2.0.0