Bump org.postgresql:postgresql from 42.5.1 to 42.7.2 in /plugin-demo

Bumps [org.postgresql:postgresql](https://github.com/pgjdbc/pgjdbc) from 42.5.1 to 42.7.2.
- [Release notes](https://github.com/pgjdbc/pgjdbc/releases)
- [Changelog](https://github.com/pgjdbc/pgjdbc/blob/master/CHANGELOG.md)
- [Commits](https://github.com/pgjdbc/pgjdbc/commits)

---
updated-dependencies:
- dependency-name: org.postgresql:postgresql
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

plugin-demo/pom.xml

@@ -101,7 +101,7 @@
                     <dependency>
                         <groupId>org.postgresql</groupId>
                         <artifactId>postgresql</artifactId>
-                        <version>42.5.1</version>
+                        <version>42.7.2</version>
                     </dependency>
                     <dependency>
                         <groupId>mysql</groupId>