cargo-apk v0.9.0

• Breaking: Use min_sdk_version to select compiler target instead of target_sdk_version. (#197)
  See https://developer.android.com/ndk/guides/sdk-versions#minsdkversion for more details.
• Breaking: Default target_sdk_version to 30 or lower (instead of the highest supported SDK version by the detected NDK toolchain)
  for more consistent interaction with Android backwards compatibility handling and its increasingly strict usage rules:
  https://developer.android.com/distribute/best-practices/develop/target-sdk
  (#203)
• Allow manifest package property to be provided in Cargo.toml. (#236)
• Add MAIN intent filter in from_subcommand instead of relying on a custom serialization function in ndk-build. (#241)
• Export the sole NativeActivity (through android:exported="true") to allow it to be started by default if targeting Android S or higher. (#242)
• cargo-apk version can now be queried through cargo apk version. (#218)
• Environment variables from .cargo/config.toml's [env] section are now propagated to the process environment. (#249)