Update to Spring Boot 2.4.2

Closes gh-227

gradle.properties

@@ -1,5 +1,5 @@
 version=0.1.0-SNAPSHOT
-springBootVersion=2.4.0
+springBootVersion=2.4.2
 org.gradle.jvmargs=-Xmx3g -XX:MaxPermSize=2048m -XX:+HeapDumpOnOutOfMemoryError
 org.gradle.parallel=true
 org.gradle.caching=true