Update GitHub actions/checkout

Author: fhunleth

.github/workflows/build.yml

@@ -22,7 +22,7 @@ jobs:
           - os: { name: Windows, runner: windows-latest }
             beam: { otp: '26', elixir: '1.15' }
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
       - uses: erlef/setup-beam@v1
         with:
@@ -107,7 +107,7 @@ jobs:
     runs-on: ubuntu-latest
     name: Extra checks
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
       - uses: erlef/setup-beam@v1
         with: