fix(deps): update dependency com.github.steveice10:mcprotocollib to v1.21.4-1

Author: renovate[bot]

build.gradle.kts

@@ -27,7 +27,7 @@ dependencies {
     implementation("org.springframework.boot:spring-boot-starter-cache")
     implementation("org.springframework.cloud:spring-cloud-starter-netflix-eureka-client")
     implementation("com.github.ben-manes.caffeine:caffeine:3.2.0")
-    implementation("com.github.Steveice10:MCProtocolLib:1.20.2-1")
+    implementation("com.github.Steveice10:MCProtocolLib:1.21.4-1")
     implementation("net.kyori:adventure-text-serializer-legacy:4.20.0")
     implementation("com.google.guava:guava:33.4.8-jre")