Bump postgresql from 42.2.5 to 42.2.6 (#5067)

Bumps [postgresql](https://github.com/pgjdbc/pgjdbc) from 42.2.5 to 42.2.6.
- [Release notes](https://github.com/pgjdbc/pgjdbc/releases)
- [Changelog](https://github.com/pgjdbc/pgjdbc/blob/master/CHANGELOG.md)
- [Commits](pgjdbc/pgjdbc@REL42.2.5...REL42.2.6)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

build.gradle

@@ -117,7 +117,7 @@ dependencies {
 
     compile 'mysql:mysql-connector-java:8.0.16'
 
-    compile 'org.postgresql:postgresql:42.2.5'
+    compile 'org.postgresql:postgresql:42.2.6'
 
     compile 'net.java.dev.glazedlists:glazedlists_java15:1.9.1'