fix: update version to 1.21.4-2.15.0-SNAPSHOT

Author: ammodev

gradle.properties

@@ -7,5 +7,5 @@ org.jetbrains.dokka.experimental.gradle.pluginMode=V2Enabled
 javaVersion=21
 mcVersion=1.21.4
 group=dev.slne.surf
-version=1.21.4-2.14.0-SNAPSHOT
+version=1.21.4-2.15.0-SNAPSHOT
 relocationPrefix=dev.slne.surf.surfapi.libs