Bump the dependencies group across 1 directory with 5 updates

Bumps the dependencies group with 5 updates in the /ktor-app directory:

| Package | From | To |
| --- | --- | --- |
| [io.mockk:mockk](https://github.com/mockk/mockk) | `1.13.12` | `1.13.13` |
| [org.testcontainers:junit-jupiter](https://github.com/testcontainers/testcontainers-java) | `1.20.2` | `1.20.3` |
| [jvm](https://github.com/JetBrains/kotlin) | `2.0.20` | `2.0.21` |
| io.ktor.plugin | `2.3.12` | `3.0.0` |
| [org.jetbrains.kotlin.plugin.serialization](https://github.com/JetBrains/kotlin) | `2.0.20` | `2.0.21` |



Updates `io.mockk:mockk` from 1.13.12 to 1.13.13
- [Release notes](https://github.com/mockk/mockk/releases)
- [Commits](mockk/mockk@1.13.12...1.13.13)

Updates `org.testcontainers:junit-jupiter` from 1.20.2 to 1.20.3
- [Release notes](https://github.com/testcontainers/testcontainers-java/releases)
- [Changelog](https://github.com/testcontainers/testcontainers-java/blob/main/CHANGELOG.md)
- [Commits](testcontainers/testcontainers-java@1.20.2...1.20.3)

Updates `jvm` from 2.0.20 to 2.0.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.0.20...v2.0.21)

Updates `io.ktor.plugin` from 2.3.12 to 3.0.0

Updates `org.jetbrains.kotlin.plugin.serialization` from 2.0.20 to 2.0.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.0.20...v2.0.21)

---
updated-dependencies:
- dependency-name: io.mockk:mockk
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: dependencies
- dependency-name: org.testcontainers:junit-jupiter
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: dependencies
- dependency-name: jvm
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: dependencies
- dependency-name: io.ktor.plugin
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: dependencies
- dependency-name: org.jetbrains.kotlin.plugin.serialization
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: dependencies
...

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

ktor-app/build.gradle.kts

@@ -8,9 +8,9 @@ val logbackVersion: String = project.property("logback_version") as String
 val postgresVersion: String = project.property("postgres_version") as String
 
 plugins {
-  kotlin("jvm") version "2.0.20"
-  id("io.ktor.plugin") version "2.3.12"
-  id("org.jetbrains.kotlin.plugin.serialization") version "2.0.20"
+  kotlin("jvm") version "2.0.21"
+  id("io.ktor.plugin") version "3.0.0"
+  id("org.jetbrains.kotlin.plugin.serialization") version "2.0.21"
   id("org.jlleitschuh.gradle.ktlint") version "12.1.1"
 }
 
@@ -52,8 +52,8 @@ dependencies {
   testImplementation("io.ktor:ktor-server-tests-jvm:$ktorVersion")
   testImplementation("org.jetbrains.kotlin:kotlin-test-junit5:$kotlinVersion")
 
-  testImplementation("io.mockk:mockk:1.13.12")
-  testImplementation("org.testcontainers:junit-jupiter:1.20.2")
+  testImplementation("io.mockk:mockk:1.13.13")
+  testImplementation("org.testcontainers:junit-jupiter:1.20.3")
   testImplementation("org.assertj:assertj-core:3.26.3")
 }