Update actions/checkout version

Author: DarthSim

.github/workflows/lint.yml

@@ -10,7 +10,7 @@ jobs:
   rubocop:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@v1
       with:
         ruby-version: 3.1

.github/workflows/test.yml

@@ -10,7 +10,7 @@ jobs:
   rspec:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@v1
       with:
         ruby-version: 3.1