Bump flatlaf from 1.6.1 to 1.6.4

Bumps [flatlaf](https://github.com/JFormDesigner/FlatLaf) from 1.6.1 to 1.6.4.
- [Release notes](https://github.com/JFormDesigner/FlatLaf/releases)
- [Changelog](https://github.com/JFormDesigner/FlatLaf/blob/main/CHANGELOG.md)
- [Commits](JFormDesigner/FlatLaf@1.6.1...1.6.4)

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

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

Author: dependabot[bot]

build.gradle.kts

@@ -17,7 +17,7 @@ dependencies {
 
     implementation("com.google.code.gson:gson:2.8.9")
 
-    implementation("com.formdev:flatlaf:1.6.1")
+    implementation("com.formdev:flatlaf:1.6.4")
 
     implementation("io.ktor:ktor-client-gson:1.6.5")
     implementation("io.ktor:ktor-client-core:1.6.5")