Bump gh actions/checkout to v4 (#83)

Author: Cristine Guadelupe

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ jobs:
               otp: 24.2.1
             lint: true
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: erlef/setup-beam@v1
         with:
           otp-version: ${{matrix.pair.otp}}