feat: Add pipelines (SCRUM-44) (!6)

SCRUM-44 #closenot

Co-authored-by: Phan Huy Tran <ptran@noreply.localhost>
Reviewed-on: #6
Co-authored-by: Jan Klattenhoff <jan@kjan.de>
Co-committed-by: Jan Klattenhoff <jan@kjan.de>

build.gradle.kts

@@ -2,14 +2,32 @@ plugins {
     java
     id("org.springframework.boot") version "3.3.4"
     id("io.spring.dependency-management") version "1.1.6"
+    id("checkstyle")
+}
+
+tasks.withType<Checkstyle> {
+    reports {
+        // Disable HTML report
+        html.required.set(false)
+
+        // Disable XML report
+        xml.required.set(false)
+    }
 }
 
 group = "de.szut"
 version = "0.0.1-SNAPSHOT"
 
+tasks.test {
+    useJUnitPlatform()
+
+    // Activate the 'test' profile for Spring during tests
+    systemProperty("spring.profiles.active", "test")
+}
+
 java {
     toolchain {
-        languageVersion = JavaLanguageVersion.of(22)
+        languageVersion = JavaLanguageVersion.of(21)
     }
 }
 
@@ -35,6 +53,7 @@ dependencies {
     implementation("org.springframework.boot:spring-boot-starter-oauth2-client:3.3.4")
     runtimeOnly("org.postgresql:postgresql")
     implementation("org.springdoc:springdoc-openapi-starter-webmvc-ui:2.6.0")
+    testImplementation("com.h2database:h2")
 }
 
 tasks.withType<Test> {