Find license from parent on OSS License Plugin.

**Describe the bug**

**To Reproduce**
Steps to reproduce the behavior:
```
$ git clone https://github.com/ganadist/minimal-reproducible-example -b oss-license
$ cd minimal-reproducible-example
$ ./gradlew :app:assembleProductionRelease
$ adb install -r app/build/outputs/apk/production/release/app-production-release.apk
```

**Expected behavior**
CommonMark license should be shown on license activity

**Desktop (please complete the following information):**
- Gradle version: Any
- Android Studio version: Any
- Plugin name and version : OSS Licenses 0.10.6

**Additional context**
On https://maven.apache.org/pom.html#inheritance , `licenses` item can be inherited from `parent`.
But, oss-licenses-plugin don't look up `licenses` item from parent.
X-posted this issue on https://github.com/commonmark/commonmark-java/issues/347