Upgrade to Spring Framework 5.1.18.RELEASE.

Author: jxblum

gradle.properties

@@ -4,7 +4,7 @@ byteBuddyVersion=1.10.14
 mockitoVersion=3.5.10
 multithreadedtcVersion=1.01
 pivotalGemFireVersion=9.5.4
-springVersion=5.1.17.RELEASE
+springVersion=5.1.18.RELEASE
 springBootVersion=2.1.17.BUILD-SNAPSHOT
 springDataGemFireVersion=2.1.19.RELEASE
 springDataGeodeVersion=2.1.19.RELEASE