keccak: test on aarch64-apple-darwin (#96)

Uses the native `macos-latest` runner.

I'm curious if this reproduces a warning I'm seeing locally.

.github/workflows/keccak.yml

@@ -51,24 +51,37 @@ jobs:
 
   test:
     needs: set-msrv
-    runs-on: ubuntu-latest
     strategy:
       matrix:
-        rust:
-          - ${{needs.set-msrv.outputs.msrv}}
-          - stable
+        include:
+          # AMD64 Linux
+          - target: x86_64-unknown-linux-gnu
+            platform: ubuntu-latest
+            rust: ${{needs.set-msrv.outputs.msrv}}
+          - target: x86_64-unknown-linux-gnu
+            platform: ubuntu-latest
+            rust: stable
+          # ARM64 macOS
+          - target: aarch64-apple-darwin
+            platform: macos-latest
+            rust: ${{needs.set-msrv.outputs.msrv}}
+          - target: aarch64-apple-darwin
+            platform: macos-latest
+            rust: stable
+    runs-on: ${{ matrix.platform }}
     steps:
       - uses: actions/checkout@v4
       - uses: RustCrypto/actions/cargo-cache@master
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust }}
-      - run: cargo check --no-default-features
-      - run: cargo check
-      - run: cargo check --features no_unroll
-      - run: cargo test --no-default-features
-      - run: cargo test
-      - run: cargo test --features no_unroll
+          targets: ${{ matrix.target }}
+      - run: cargo check --no-default-features --target ${{ matrix.target }}
+      - run: cargo check --target ${{ matrix.target }}
+      - run: cargo check --features no_unroll --target ${{ matrix.target }}
+      - run: cargo test --no-default-features --target ${{ matrix.target }}
+      - run: cargo test --target ${{ matrix.target }}
+      - run: cargo test --features no_unroll --target ${{ matrix.target }}
 
   test-simd:
     runs-on: ubuntu-latest