Remove unnecessary toolchain override

Author: kl

.github/workflows/rust-unused-dependencies.yml

@@ -91,7 +91,7 @@ jobs:
           tool: cargo-udeps
 
       - name: Check for unused dependencies
-        run: cargo +${{ env.RUST_NIGHTLY_TOOLCHAIN }} udeps --target aarch64-linux-android --package mullvad-jni
+        run: cargo udeps --target aarch64-linux-android --package mullvad-jni
 
   cargo-udeps:
     strategy: