Run SonarCloud analysis with Java 11

[beatngu13]

As pointed in issue #267, SonarCloud will drop support for Java 8 by October 2020. This PR will run the SonarCloud analysis with Java 11, while still using Java 8 source level. At least this is how I interpret the docs:

https://docs.sonarqube.org/latest/analysis/scan/sonarscanner-for-gradle/

Here it says sonar.java.source defaults to ${project.sourceCompatibility}, which we have set to 8 here:

https://github.com/junit-pioneer/junit-pioneer/blob/master/build.gradle.kts#L16

Proposed commit message:

Run SonarCloud analysis with Java 11

As pointed in issue #267, SonarCloud will drop support for Java 8 by
October 2020. This PR will run the SonarCloud analysis with Java 11,
while still using Java 8 source level.

Closes: #267
PR: #268

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[sonarcloud]

Kudos, SonarCloud Quality Gate passed!

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0 Vulnerabilities (and 0 Security Hotspots to review)
0 Code Smells

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[aepfli]

thank you!