Bump actions/checkout from 3 to 4 (#13)

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...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>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/check.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     name: stable / fmt
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install stable
@@ -34,7 +34,7 @@ jobs:
       matrix:
         toolchain: [stable, beta]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install ${{ matrix.toolchain }}
@@ -50,7 +50,7 @@ jobs:
     runs-on: ubuntu-latest
     name: nightly / doc
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install nightly
@@ -63,7 +63,7 @@ jobs:
     runs-on: ubuntu-latest
     name: ubuntu / stable / features
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install stable
@@ -82,7 +82,7 @@ jobs:
         msrv: ["1.56.1"] # 2021 edition requires 1.56
     name: ubuntu / ${{ matrix.msrv }}
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install ${{ matrix.msrv }}

.github/workflows/nostd.yml

@@ -17,7 +17,7 @@ jobs:
       matrix:
         target: [thumbv7m-none-eabi, aarch64-unknown-none]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install stable

.github/workflows/safety.yml

@@ -13,7 +13,7 @@ jobs:
   sanitizers:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install nightly
@@ -49,7 +49,7 @@ jobs:
   miri:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - run: |
@@ -66,7 +66,7 @@ jobs:
   loom:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install stable

.github/workflows/scheduled.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-latest
     name: ubuntu / nightly
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install nightly
@@ -36,7 +36,7 @@ jobs:
     # Unfortunately, hashFiles only works in if on steps, so we reepeat it.
     # if: hashFiles('Cargo.lock') != ''
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install beta

.github/workflows/test.yml

@@ -17,7 +17,7 @@ jobs:
       matrix:
         toolchain: [stable, beta]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install ${{ matrix.toolchain }}
@@ -37,7 +37,7 @@ jobs:
     runs-on: ubuntu-latest
     name: ubuntu / stable / minimal-versions
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install stable
@@ -64,7 +64,7 @@ jobs:
       #   if: runner.os == 'Windows'
       # - run: vcpkg install openssl:x64-windows-static-md
       #   if: runner.os == 'Windows'
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install stable
@@ -78,7 +78,7 @@ jobs:
     runs-on: ubuntu-latest
     name: ubuntu / stable / coverage
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install stable