chore(deps): bump actions/checkout from 1 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 1 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v1...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.yml

@@ -13,7 +13,7 @@ jobs:
   security_audit:
     runs-on: ubuntu-20.04
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - uses: actions-rs/audit-check@v1
         with:
           token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/code_coverage.yml

@@ -13,7 +13,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: Install lcov tools
         run: sudo apt-get install lcov -y
       - name: Install Rust toolchain

.github/workflows/cont_integration.yml

@@ -18,7 +18,7 @@ jobs:
           - --all-features
     steps:
       - name: checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: Install Rust toolchain
         uses: actions-rs/toolchain@v1
         with:
@@ -43,7 +43,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: Install Rust toolchain
         uses: actions-rs/toolchain@v1
         with:
@@ -74,7 +74,7 @@ jobs:
       CFLAGS: -I/usr/include
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         # Install a recent version of clang that supports wasm32
       - run: wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add - || exit 1
       - run: sudo apt-get update || exit 1
@@ -100,7 +100,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: Install Rust toolchain
         uses: actions-rs/toolchain@v1
         with:
@@ -114,7 +114,7 @@ jobs:
   clippy_check:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v4
       - uses: actions-rs/toolchain@v1
         with:
             toolchain: stable

.github/workflows/nightly_docs.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout sources
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: Set default toolchain
         run: rustup default nightly-2022-12-14
       - name: Set profile
@@ -34,7 +34,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout `bitcoindevkit.org`
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           ssh-key: ${{ secrets.DOCS_PUSH_SSH_KEY }}
           repository: bitcoindevkit/bitcoindevkit.org