Bump actions/checkout from 2 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/audit.yaml

@@ -11,7 +11,7 @@ jobs:
   security_audit:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: actions-rs/audit-check@35b7b53b1e25b55642157ac01b4adceb5b9ebef3
         with:
           token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/test.yaml

@@ -33,7 +33,7 @@ jobs:
 
     steps:
       - name: checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install Rust ${{ matrix.rust }}
         uses: dtolnay/rust-toolchain@master
@@ -57,7 +57,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
 
       - name: Install Rust
         uses: actions-rs/toolchain@v1
@@ -91,7 +91,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install Rust
         uses: dtolnay/rust-toolchain@stable
@@ -103,7 +103,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install Rust stable
         uses: dtolnay/rust-toolchain@stable
@@ -119,7 +119,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install Rust stable
         uses: dtolnay/rust-toolchain@stable
@@ -135,7 +135,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install Rust nightly
         uses: dtolnay/rust-toolchain@nightly