Bump checkout to v4

.github/workflows/rust.yml

@@ -26,14 +26,14 @@ jobs:
   fmt:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - run: rustup update
     - run: cargo fmt --all --check
 
   cackle:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: cackle-rs/cackle-action@997327f77e59d9cda7b0b6217f0fbdbd3f3ca904
       - run: cargo acl -n run
 
@@ -47,21 +47,21 @@ jobs:
     # Prevent sudden announcement of a new advisory from failing ci:
     continue-on-error: ${{ matrix.checks == 'advisories' }}
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - uses: EmbarkStudios/cargo-deny-action@b01e7a8cfb1f496c52d77361e84c1840d8246393
       with:
         command: check ${{ matrix.checks }}
 
   check-git-rev-deps:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - uses: stellar/actions/rust-check-git-rev-deps@main
 
   semver-checks:    
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3`
+    - uses: actions/checkout@v4`
     - run: rustup update
     - uses: stellar/binaries@v33
       with:
@@ -93,7 +93,7 @@ jobs:
         #   test: true
     runs-on: ${{ matrix.sys.os }}
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - uses: stellar/actions/rust-cache@main
     - name: Use the minimum supported Rust version
       if: matrix.rust == 'msrv'