Bump maven-compiler-plugin from 3.7.0 to 3.8.1 in /core
Bump maven-compiler-plugin from 3.7.0 to 3.8.1 in /core

Bumps [maven-compiler-plugin](https://github.com/apache/maven-compiler-plugin) from 3.7.0 to 3.8.1.
- [Release notes](https://github.com/apache/maven-compiler-plugin/releases)
- [Commits](https://github.com/apache/maven-compiler-plugin/compare/maven-compiler-plugin-3.7.0...maven-compiler-plugin-3.8.1)

Signed-off-by: dependabot[bot] <support@github.com>

Closes #93

Change-Id: Ie2594c5bd1be8dc856a709451ad74600720ea79b

KorAP/Kustvakt,KorAP/Kustvakt,KorAP/Kustvakt,KorAP/Kustvakt