Update CI dependency versions. (#139)

Author: sunfishcode

.github/workflows/main.yml

@@ -17,7 +17,7 @@ jobs:
     env:
       RUSTFLAGS: -D warnings
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - run: |
         rustup set profile minimal
         rustup install ${{ matrix.rust }}
@@ -35,7 +35,7 @@ jobs:
       # -D warnings is commented out in our install-rust action; re-add it here.
       RUSTFLAGS: -D warnings
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
       with:
         submodules: true
     - uses: ./.github/actions/install-rust
@@ -70,7 +70,7 @@ jobs:
     name: Update generated files
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - run: |
         wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
         sudo add-apt-repository -y 'deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy main'