Remove redundant RUSTFLAGS from cross test job in CI workflow

Author: stevefan1999-personal

.github/workflows/rustls-rustcrypto.yml

@@ -100,6 +100,4 @@ jobs:
           toolchain: ${{ matrix.rust }}
           targets: ${{ matrix.target }}
       - uses: RustCrypto/actions/cross-install@master
-      - run: cross test --release --target ${{ matrix.target }} --all-features
-        env: 
-          RUSTFLAGS: --cfg getrandom_backend="custom"
+      - run: cross test --release --target ${{ matrix.target }} --all-features