ci: fix nightly clippy

Remove `--all-features` from the clippy command because

1. with the removal of `cocunut` it's not really needed
2. the new `mobile` flag is a bit hacky and mutually incompatible with
   some existing configs

.github/workflows/nightly_build.yml

@@ -106,7 +106,7 @@ jobs:
         if: ${{ matrix.rust != 'nightly' }}
         with:
           command: clippy
-          args: --workspace --all-targets -- -D warnings
+          args: --workspace -- -D warnings
 
       - name: Reclaim some disk space
         uses: actions-rs/cargo@v1