Call rustup manually, since the action doesn't seem to work.

.github/workflows/test.yml

@@ -71,13 +71,13 @@ jobs:
         with:
           profile: minimal
           toolchain: stable
-          target: aarch64-linux-android, armv7-linux-androideabi, i686-linux-android, x86_64-linux-android
           components: rustfmt, clippy
           override: true
       - uses: actions-rs/install@v0.1
         with:
           crate: cargo-apk
           # use-tool-cache: true
+      - run: rustup target add aarch64-linux-android armv7-linux-androideabi i686-linux-android x86_64-linux-android
       - uses: actions-rs/cargo@v1
         with:
           command: apk