ci(rust): remove explicit RUSTFLAGS env from test step

Author: blackopsrepl

.github/workflows/ci.yml

@@ -74,8 +74,6 @@ jobs:
         run: cargo build --workspace --all-features
 
       - name: Run tests
-        env:
-          RUSTFLAGS: ${{ matrix.rustflags }}
         run: cargo test --workspace --all-features
 
   integration: