Bump mockitoVersion from 5.3.1 to 5.4.0

Bumps `mockitoVersion` from 5.3.1 to 5.4.0.

Updates `org.mockito:mockito-core` from 5.3.1 to 5.4.0
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v5.3.1...v5.4.0)

Updates `org.mockito:mockito-junit-jupiter` from 5.3.1 to 5.4.0
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v5.3.1...v5.4.0)

---
updated-dependencies:
- dependency-name: org.mockito:mockito-core
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.mockito:mockito-junit-jupiter
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

build.gradle.kts

@@ -56,7 +56,7 @@ dependencies {
     runtimeOnly("com.fasterxml.jackson.module:jackson-module-kotlin")
 
     testImplementation("io.projectreactor:reactor-test:3.5.6")
-    val mockitoVersion = "5.3.1"
+    val mockitoVersion = "5.4.0"
     testImplementation("org.mockito:mockito-core:$mockitoVersion")
     testImplementation("org.mockito:mockito-junit-jupiter:$mockitoVersion")
     testImplementation("org.mockito.kotlin:mockito-kotlin:5.0.0")