ci: remove unnecessary rustfmt check steps

`cargo fmt` is already pre-installed in ubuntu-latest

.github/workflows/ci.yml

@@ -18,14 +18,6 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
-      - uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-          override: true
-      - run: rustup component add rustfmt
-      - name: Cache rust cargo artifacts
-        uses: swatinem/rust-cache@v2
       - run: cargo fmt --all -- --check
 
   run_clippy: