Bump actions/checkout from 3 to 4

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>

Author: dependabot[bot]

.github/workflows/check.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     name: nightly / fmt
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install nightly
@@ -30,7 +30,7 @@ jobs:
       matrix:
         toolchain: [nightly]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install ${{ matrix.toolchain }}
@@ -46,7 +46,7 @@ jobs:
     runs-on: ubuntu-latest
     name: nightly / doc
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install nightly
@@ -59,7 +59,7 @@ jobs:
     runs-on: ubuntu-latest
     name: ubuntu / nightly / features
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install nightly
@@ -79,7 +79,7 @@ jobs:
 #       msrv: [1.61.0] # `impl Trait` requires this
 #   name: ubuntu / ${{ matrix.msrv }}
 #   steps:
-#     - uses: actions/checkout@v3
+#     - uses: actions/checkout@v4
 #       with:
 #         submodules: true
 #     - name: Install ${{ matrix.msrv }}

.github/workflows/nostd.yml

@@ -13,7 +13,7 @@ jobs:
       matrix:
         target: [thumbv7m-none-eabi, aarch64-unknown-none]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install nightly

.github/workflows/safety.yml

@@ -9,7 +9,7 @@ jobs:
   sanitizers:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install nightly
@@ -38,7 +38,7 @@ jobs:
   miri:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - run: |
@@ -55,7 +55,7 @@ jobs:
 # loom:
 #   runs-on: ubuntu-latest
 #   steps:
-#     - uses: actions/checkout@v3
+#     - uses: actions/checkout@v4
 #       with:
 #         submodules: true
 #     - name: Install nightly

.github/workflows/scheduled.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     name: ubuntu / nightly
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install nightly
@@ -34,7 +34,7 @@ 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 nightly

.github/workflows/test.yml

@@ -13,7 +13,7 @@ jobs:
       matrix:
         toolchain: [nightly]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install ${{ matrix.toolchain }}
@@ -38,7 +38,7 @@ jobs:
       matrix:
         os: [macos-latest, windows-latest]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - name: Install nightly