ci: detect unused dependencies with cargo-machete

Author: bnjbvr

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

@@ -0,0 +1,12 @@
+name: Detects unused dependencies
+on:
+  pull_request: { branches: "*" }
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Machete
+        uses: bnjbvr/cargo-machete@main