ci: Use checkout@v4

Author: bluss

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
           - 1.51.0  # MSRV
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust }}
@@ -45,7 +45,7 @@ jobs:
             target: i686-unknown-linux-gnu
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust }}
@@ -62,7 +62,7 @@ jobs:
         rust:
           - beta
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust }}