(PA-5803) Update Checkout GitHub Action

The Checkout GitHub Action v3 uses Node 16, which hit end-of-life on
September 11, 2023.

This commit updates all instances of the Checkout Action from v3 to
v4.

Author: mhashizume

.github/workflows/checks.yaml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout current PR
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
       - uses: ruby/setup-ruby@v1
@@ -33,7 +33,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout current PR
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
       - uses: ruby/setup-ruby@v1

.github/workflows/mend.yaml

@@ -11,7 +11,7 @@ jobs:
     name: Mend Monitor
     steps:
       - name: Checkout current PR
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Setup Ruby
         uses: ruby/setup-ruby@v1
         with:

.github/workflows/release.yaml

@@ -9,7 +9,7 @@ jobs:
   release:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           fetch-depth: '0'
       - name: Build gem

.github/workflows/rspec_tests.yaml

@@ -24,7 +24,7 @@ jobs:
       PUPPET_GEM_VERSION: ~> ${{ matrix.cfg.puppet_version }}
     steps:
       - name: Checkout current PR
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
       - name: Install Ruby version ${{ matrix.cfg.ruby }}
@@ -53,7 +53,7 @@ jobs:
       PUPPET_GEM_VERSION: ~> ${{ matrix.cfg.puppet_version }}
     steps:
       - name: Checkout current PR
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
       - name: Install Ruby version ${{ matrix.cfg.ruby }}