Bump kotestVersion from 5.9.0 to 5.9.1

Bumps `kotestVersion` from 5.9.0 to 5.9.1.

Updates `io.kotest:kotest-runner-junit5` from 5.9.0 to 5.9.1
- [Release notes](https://github.com/kotest/kotest/releases)
- [Commits](kotest/kotest@v5.9.0...v5.9.1)

Updates `io.kotest:kotest-assertions-core` from 5.9.0 to 5.9.1
- [Release notes](https://github.com/kotest/kotest/releases)
- [Commits](kotest/kotest@v5.9.0...v5.9.1)

---
updated-dependencies:
- dependency-name: io.kotest:kotest-runner-junit5
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: io.kotest:kotest-assertions-core
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

plugin/build.gradle.kts

@@ -31,7 +31,7 @@ dependencies {
 
     implementation("net.sourceforge.plantuml:plantuml:1.2024.5")
 
-    val kotestVersion = "5.9.0"
+    val kotestVersion = "5.9.1"
     testImplementation("io.kotest:kotest-runner-junit5:$kotestVersion")
     testImplementation("io.kotest:kotest-assertions-core:$kotestVersion")
 }