Bump actions/checkout from 4 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/local_openssl.yml

@@ -28,7 +28,7 @@ jobs:
           - stable
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: RustCrypto/actions/cargo-cache@master
       - uses: dtolnay/rust-toolchain@master
         with:

.github/workflows/rustls-rustcrypto.yml

@@ -20,7 +20,7 @@ jobs:
   clippy:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: 1.85.0
@@ -30,7 +30,7 @@ jobs:
   doc:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: stable
@@ -39,7 +39,7 @@ jobs:
   rustfmt:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: stable
@@ -58,7 +58,7 @@ jobs:
           - thumbv7em-none-eabi
           - wasm32-unknown-unknown
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust }}
@@ -75,7 +75,7 @@ jobs:
           - stable
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: RustCrypto/actions/cargo-cache@master
       - uses: dtolnay/rust-toolchain@master
         with:
@@ -94,7 +94,7 @@ jobs:
             rust: stable
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - run: ${{ matrix.deps }}
       - uses: dtolnay/rust-toolchain@master
         with: