bump actions/checkout to v4

.github/workflows/ci.yml

@@ -15,7 +15,7 @@ jobs:
   # checklinks:
   #   runs-on: ubuntu-latest
   #   steps:
-  #     - uses: actions/checkout@v3
+  #     - uses: actions/checkout@v4
 
   #     - uses: trevyn/lychee-action@v1
   #       id: lychee
@@ -37,7 +37,7 @@ jobs:
         rust: ["1.56.1", stable, beta, nightly]
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - run: rustup default ${{ matrix.rust }} && rustup update ${{ matrix.rust }}
 
@@ -55,7 +55,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - run: rustup default nightly && rustup update nightly
 
@@ -71,7 +71,7 @@ jobs:
     if: ${{ startsWith(github.event.head_commit.message, 'tracked@') && github.event_name == 'push' && github.ref == 'refs/heads/main' }}
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - run: rustup default stable && rustup update stable