Bump incrementals-plugin.version from 1.5 to 1.6

Bumps `incrementals-plugin.version` from 1.5 to 1.6.

Updates `incrementals-enforcer-rules` from 1.5 to 1.6
- [Release notes](https://github.com/jenkinsci/incrementals-tools/releases)
- [Commits](jenkinsci/incrementals-tools@parent-1.5...parent-1.6)

Updates `incrementals-maven-plugin` from 1.5 to 1.6
- [Release notes](https://github.com/jenkinsci/incrementals-tools/releases)
- [Commits](jenkinsci/incrementals-tools@parent-1.5...parent-1.6)

---
updated-dependencies:
- dependency-name: io.jenkins.tools.incrementals:incrementals-enforcer-rules
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: io.jenkins.tools.incrementals:incrementals-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

pom.xml

@@ -75,7 +75,7 @@
     <gmavenplus-plugin.version>2.1.0</gmavenplus-plugin.version>
     <hpi-plugin.version>3.38</hpi-plugin.version>
     <incrementals-enforce-minimum.version>1.0-beta-4</incrementals-enforce-minimum.version>
-    <incrementals-plugin.version>1.5</incrementals-plugin.version>
+    <incrementals-plugin.version>1.6</incrementals-plugin.version>
     <jacoco-maven-plugin.version>0.8.8</jacoco-maven-plugin.version>
     <jenkins.version>2.361</jenkins.version>
     <jenkins-bom.version>${jenkins.version}</jenkins-bom.version>