Delete deprecated action step

Author: tazz4843

.github/workflows/linters.yml

@@ -32,7 +32,6 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - uses: rui314/setup-mold@v1
-      - uses: actions-rs/toolchain@v1
       - uses: actions-rust-lang/setup-rust-toolchain@v1
         with:
           toolchain: nightly