CI/CD failed even just modified documentation.

[cheqianh]

The CI/CD run into a failure even when just modified document. It only happens on GHA right now (I couldn't repro it locally). This might because of the environment change in GHA.

Example log - https://github.com/amazon-ion/ion-hive-serde/actions/runs/3989986409/jobs/6843077268

Here are the highlights of this release:
 - Feature variants AKA "optional dependencies"
 - Type-safe accessors in Kotlin precompiled script plugins
 - Gradle Module Metadata 1.0

For more details see https://docs.gradle.org/5.3.1/release-notes.html

Starting a Gradle Daemon (subsequent builds will be faster)
> Task :serde:compileKotlin
> Task :serde:compileJava FAILED

Deprecated Gradle features were used in this build, making it incompatible with Gradle 6.0.
FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':serde:compileJava'.
> java.lang.reflect.UndeclaredThrowableException

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in [30](https://github.com/amazon-ion/ion-hive-serde/actions/runs/3989986409/jobs/6843077268#step:4:31)s
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/5.3.1/userguide/command_line_interface.html#sec:command_line_warnings
2 actionable tasks: 2 executed
Error: Process completed with exit code 1.

[jobarr-amzn]

This build failure is on Java 10.

I'm tempted to restrict our build matrix to LTS JDKs, i.e. 8 and 11 instead of 8, 9, 10, 11.