Move dependencies to gradle version catalog and clean up buildscripts

build.gradle.kts

@@ -6,11 +6,9 @@ plugins {
     `java-library`
 }
 
-val junitVersion: String by project.extra
-
 allprojects {
     group = "com.velocitypowered"
-    version = "3.2.0-SNAPSHOT"
+    version = rootProject.file("version").readLines().first()
 }
 
 subprojects {
@@ -31,8 +29,9 @@ subprojects {
         maven("https://s01.oss.sonatype.org/content/repositories/snapshots/") // adventure
         maven("https://repo.papermc.io/repository/maven-public/")
     }
+
     dependencies {
-        testImplementation("org.junit.jupiter:junit-jupiter:$junitVersion")
+        testImplementation(rootProject.libs.junit)
     }
 
     tasks {