fix: use log4j2 and slf4j versions that match spring-boot-starter-log4j2 2.2.1.RELEASE

Author: Alan Scherger

build.gradle

@@ -38,8 +38,8 @@ subprojects {
     ext['rsocket.version'] = '1.0.0-RC5'
     ext['graphql.version'] = '11.0'
     ext['protobuf.version'] = '3.6.1'
-    ext['log4j.version'] = '2.11.2'
-    ext['slf4j.version'] = '1.8.0-beta2'
+    ext['log4j.version'] = '2.12.1'
+    ext['slf4j.version'] = '1.7.29'
     ext['junit.version'] = '5.4.0'
     ext['mockito.version'] = '2.23.0'
     ext['hamcrest.version'] = '1.3'