Update workflow to actions/checkout@v4

This fixes a warning about Node 16 being deprecated

Author: jannic

.github/workflows/clippy.yml

@@ -10,7 +10,7 @@ jobs:
   clippy:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@master
         with:
           # embedded-hal-async needs nightly.

.github/workflows/rustdoc.yml

@@ -10,7 +10,7 @@ jobs:
   clippy:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: nightly-2023-10-14

.github/workflows/rustfmt.yml

@@ -11,7 +11,7 @@ jobs:
   fmt:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: nightly

.github/workflows/test.yml

@@ -14,21 +14,21 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
       - run: cargo test --workspace
 
   test-all-features:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
       - run: cargo test --workspace --all-features
 
   build-nostd:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
         with:
           target: thumbv7m-none-eabi
@@ -41,7 +41,7 @@ jobs:
   msrv-1-60:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@1.60
       - run: >
           cargo test
@@ -55,6 +55,6 @@ jobs:
   msrv-1-75:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@1.75
       - run: cargo test --workspace --all-features