Py-hiverunner

Fixed
- NullPointerException in tearDown of `StandaloneHiveRunner`.

Changed
- Upgraded Hive version to 2.3.7 (was 2.3.6) (allows HiveRunner to be used on JDK>=9).

Changed
- Upgraded Hive version to 2.3.6 (was 2.3.4).

Changed
- Upgraded JUnit Jupiter version to 5.6.0 (was 5.5.1).
- Depend on `junit-jupiter` instead of `junit-jupiter-api`.

Added
- JUnit5 [Extension](https://junit.org/junit5/docs/current/user-guide/extensions) support with `HiveRunnerExtension`. See [106](https://github.com/klarna/HiveRunner/issues/106).

Changed
- Default supported Hive version is now 2.3.4 (was 2.3.3) as version 2.3.3 has a [vulnerability](https://nvd.nist.gov/vuln/detail/CVE-2018-1314).
- `TemporaryFolder` ([JUnit 4](https://junit.org/junit4/javadoc/4.12/org/junit/rules/TemporaryFolder.html)) has been changed to `Path` ([Java NIO](https://docs.oracle.com/javase/8/docs/api/java/nio/file/Path.html)) throughout the project for the JUnit5 update.
- NOTE: The `HiveServerContext` class now uses `Path` instead of `TemporaryFolder` in the constructor.

Changed
- Internal refactoring to support upcoming "Mutant Swarm" project which provides unit test coverage for Hive SQL scripts. See [65](https://github.com/klarna/HiveRunner/issues/65).