Fix CI cache key

.github/workflows/rust.yml

@@ -31,7 +31,7 @@ jobs:
           ~/.cargo/registry/cache/
           ~/.cargo/git/db/
           target/
-        key: ${{ runner.os }}-cargo-build-${{steps.toolchain.outputs.cachekey}}-${{ hashFiles('**/Cargo.toml') }}
+        key: ${{ runner.os }}-cargo-build-1.70.0-${{ hashFiles('**/Cargo.toml') }}
     - name: Install alsa and udev
       run: sudo apt-get update; sudo apt-get install --no-install-recommends libasound2-dev libudev-dev libwayland-dev libxkbcommon-dev
       if: runner.os == 'linux'