ci: fix coverage job

We no longer need to run it with nightly.

Author: gdesmott

.github/workflows/ci.yml

@@ -90,8 +90,6 @@ jobs:
       - uses: actions/checkout@v1
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: nightly
-          override: true
           components: llvm-tools-preview
       - uses: actions-rs/cargo@v1
         with: