Fix style.yml: Set override to true when installing toolchain

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

Author: NobodyXu

.github/workflows/style.yml

@@ -29,6 +29,7 @@ jobs:
           profile: minimal
           toolchain: ${{ matrix.toolchain }}
           components: rustfmt, clippy
+          override: true
       - uses: actions/checkout@v2
       - name: cargo fmt --check
         uses: actions-rs/cargo@v1