ci: switch to actions/checkout@v3

I saw the following warning on GitHub Actions:

    Node.js 12 actions are deprecated. Please update the following
    actions to use Node.js 16: actions/checkout@v2. For more information
    see: https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/.

Updating seems quite reasonable to me.

.github/workflows/build-macos.yml

@@ -103,7 +103,7 @@ jobs:
         run: |
           HOMEBREW_NO_AUTO_UPDATE=1 brew install llvm@15
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - name: Install Go
         uses: actions/setup-go@v3
         with:

.github/workflows/windows.yml

@@ -108,7 +108,7 @@ jobs:
         run: |
           scoop install binaryen
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - name: Install Go
         uses: actions/setup-go@v3
         with:
@@ -132,7 +132,7 @@ jobs:
     needs: build-windows
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - name: Install Go
         uses: actions/setup-go@v3
         with:
@@ -162,7 +162,7 @@ jobs:
         run: |
           scoop install binaryen wasmtime
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - name: Install Go
         uses: actions/setup-go@v3
         with: