Bump com.spotify.ruler:ruler-gradle-plugin from 1.2.1 to 1.4.0

Bumps [com.spotify.ruler:ruler-gradle-plugin](https://github.com/spotify/ruler) from 1.2.1 to 1.4.0.
- [Release notes](https://github.com/spotify/ruler/releases)
- [Changelog](https://github.com/spotify/ruler/blob/main/changelog.md)
- [Commits](spotify/ruler@v1.2.1...v1.4.0)

---
updated-dependencies:
- dependency-name: com.spotify.ruler:ruler-gradle-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

buildSrc/build.gradle.kts

@@ -16,7 +16,7 @@ dependencies {
   implementation("app.cash.licensee:licensee-gradle-plugin:1.3.0")
   implementation("com.osacky.flank.gradle:fladle:0.17.4")
 
-  implementation("com.spotify.ruler:ruler-gradle-plugin:1.2.1")
+  implementation("com.spotify.ruler:ruler-gradle-plugin:1.4.0")
 
   implementation("ca.uhn.hapi.fhir:hapi-fhir-structures-r4:6.8.0")
   implementation("com.squareup:kotlinpoet:1.14.2")