chore: update actions/checkout action to v3 (#104)

Author: taiki-e

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Build
       run: cargo build --verbose
     - name: Build with OTel feature
@@ -25,4 +25,4 @@ jobs:
       uses: actions-rs/cargo@v1
       with:
         command: fmt
-        args: --all -- --check
+        args: --all -- --check