chore(deps): bump to Spring Boot 2.4.0

Author: hantsy

server/build.gradle.kts

@@ -1,10 +1,10 @@
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
 plugins {
-	id("org.springframework.boot") version "2.4.0-M1"
-	id("io.spring.dependency-management") version "1.0.9.RELEASE"
-	kotlin("jvm") version "1.3.72"
-	kotlin("plugin.spring") version "1.3.72"
+	id("org.springframework.boot") version "2.4.0"
+	id("io.spring.dependency-management") version "1.0.10.RELEASE"
+	kotlin("jvm") version "1.4.10"
+	kotlin("plugin.spring") version "1.4.10"
 }
 
 group = "com.example"