[server] update to SpringBoot 2.3

Also updates Jackson dependency to `2.11.3`.

Resolves: ExpediaGroup#850

gradle.properties

@@ -20,13 +20,13 @@ kotlinCoroutinesVersion = 1.3.8
 
 classGraphVersion = 4.8.87
 graphQLJavaVersion = 15.0
-jacksonVersion = 2.11.0
+jacksonVersion = 2.11.3
 kotlinPoetVersion = 1.6.0
 ktorVersion = 1.3.1
-reactorVersion = 3.3.6.RELEASE
+reactorVersion = 3.3.10.RELEASE
 reactorExtensionsVersion = 1.0.2.RELEASE
-springBootVersion = 2.2.9.RELEASE
-springVersion = 5.2.8.RELEASE
+springBootVersion = 2.3.4.RELEASE
+springVersion = 5.2.9.RELEASE
 
 # test dependency versions
 junitVersion = 5.6.2