Update workflows to actions/checkout@v3

Author: dtolnay

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
       matrix:
         rust: [1.31.0, stable, beta]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{matrix.rust}}
@@ -37,7 +37,7 @@ jobs:
     name: Rust nightly
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: dtolnay/rust-toolchain@nightly
       - run: cargo test
       - run: cargo test --no-default-features
@@ -62,7 +62,7 @@ jobs:
     name: WebAssembly
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: dtolnay/rust-toolchain@nightly
         with:
           target: wasm32-unknown-unknown
@@ -73,7 +73,7 @@ jobs:
     runs-on: ubuntu-latest
     if: github.event_name != 'pull_request'
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: dtolnay/rust-toolchain@clippy
       - run: cargo clippy --tests -- -Dclippy::all -Dclippy::pedantic
       - run: cargo clippy --tests --all-features -- -Dclippy::all -Dclippy::pedantic
@@ -83,6 +83,6 @@ jobs:
     runs-on: ubuntu-latest
     if: github.event_name != 'pull_request'
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: dtolnay/install@cargo-outdated
       - run: cargo outdated --exit-code 1