Update actions/checkout in GitHub Actions workflows to v4

Author: striezel

.github/workflows/main.yml

@@ -29,7 +29,7 @@ jobs:
             os: windows-2022
             rust: stable-x86_64-gnu
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Install Rust (rustup)
       run: rustup update ${{ matrix.rust }} --no-self-update && rustup default ${{ matrix.rust }}
       shell: bash
@@ -58,7 +58,7 @@ jobs:
     name: Rustfmt
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Install Rust
       run: rustup update stable && rustup default stable && rustup component add rustfmt
     - run: cargo fmt -- --check
@@ -70,7 +70,7 @@ jobs:
       matrix:
         target: [wasm32-unknown-unknown, wasm32-wasi]
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Install Rust
       run: rustup update stable && rustup default stable && rustup target add ${{ matrix.target }}
     - run: cargo build --target ${{ matrix.target }}