Update to Spring Boot 2.4.0-M3

Closes gh-9107

Author: jzheaux

gradle.properties

@@ -1,7 +1,7 @@
 aspectjVersion=1.9.3
 gaeVersion=1.9.80
 springJavaformatVersion=0.0.24
-springBootVersion=2.4.0-M1
+springBootVersion=2.4.0-M3
 version=5.4.1-SNAPSHOT
 kotlinVersion=1.3.72
 org.gradle.jvmargs=-Xmx3g -XX:MaxPermSize=2048m -XX:+HeapDumpOnOutOfMemoryError