Bump flatlaf from 1.5 to 1.6 (#14)

Bumps [flatlaf](https://github.com/JFormDesigner/FlatLaf) from 1.5 to 1.6.
- [Release notes](https://github.com/JFormDesigner/FlatLaf/releases)
- [Changelog](https://github.com/JFormDesigner/FlatLaf/blob/main/CHANGELOG.md)
- [Commits](JFormDesigner/FlatLaf@1.5...1.6)

---
updated-dependencies:
- dependency-name: com.formdev:flatlaf
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

build.gradle

@@ -41,7 +41,7 @@ dependencies {
     include "com.google.code.gson:gson:2.8.8"
     include "com.github.zafarkhaja:jsemver:0.9.0"
 
-    include 'com.formdev:flatlaf:1.5'
+    include 'com.formdev:flatlaf:1.6'
 
     include "io.ktor:ktor-client-gson:1.6.4"
     include "io.ktor:ktor-client-core:1.6.3"