Update to Spring Boot 2.4.8

Closes gh-10181

gradle.properties

@@ -1,7 +1,7 @@
 aspectjVersion=1.9.6
 gaeVersion=1.9.86
 springJavaformatVersion=0.0.25
-springBootVersion=2.4.4
+springBootVersion=2.4.8
 version=5.4.8-SNAPSHOT
 kotlinVersion=1.4.30
 org.gradle.jvmargs=-Xmx3g -XX:MaxPermSize=2048m -XX:+HeapDumpOnOutOfMemoryError