Bump com.io7m.quarrel:com.io7m.quarrel.ext.logback from 1.4.0 to 1.6.0

Bumps [com.io7m.quarrel:com.io7m.quarrel.ext.logback](https:/io7m/quarrel) from 1.4.0 to 1.6.0.
- [Changelog](https:/io7m/quarrel/blob/develop/README-CHANGES.xml)
- [Commits](io7m-com/quarrel@com.io7m.quarrel-1.4.0...com.io7m.quarrel-1.6.0)

---
updated-dependencies:
- dependency-name: com.io7m.quarrel:com.io7m.quarrel.ext.logback
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

pom.xml

@@ -211,7 +211,7 @@
  <dependency>
  <groupId>com.io7m.quarrel</groupId>
  <artifactId>com.io7m.quarrel.ext.logback</artifactId>
- <version>1.4.0</version>
+ <version>1.6.0</version>
  </dependency>
 
  <!-- Test suite -->