Install bindgen-cli in Kotlin CI

By default `rustls`, our TLS implementation of choice, uses `aws-lc-rs`
which requires `bindgen` on some platforms. To allow building with
`aws-lc-rs` on Android, we here install the `bindgen-cli` tool before
running the bindings generation script in CI.

Author: tnull

.github/workflows/kotlin.yml

@@ -39,6 +39,9 @@ jobs:
       - name: Generate Kotlin JVM
         run: ./scripts/uniffi_bindgen_generate_kotlin.sh
 
+      - name: Install `bindgen-cli`
+        run: cargo install --force bindgen-cli
+
       - name: Generate Kotlin Android
         run: ./scripts/uniffi_bindgen_generate_kotlin_android.sh