build(deps): bump org.postgresql:postgresql in /samples/java/jdbc (GoogleCloudPlatform#4144)

Bumps [org.postgresql:postgresql](https://github.com/pgjdbc/pgjdbc) from 42.7.9 to 42.7.10.
- [Release notes](https://github.com/pgjdbc/pgjdbc/releases)
- [Changelog](https://github.com/pgjdbc/pgjdbc/blob/master/CHANGELOG.md)
- [Commits](pgjdbc/pgjdbc@REL42.7.9...REL42.7.10)

---
updated-dependencies:
- dependency-name: org.postgresql:postgresql
  dependency-version: 42.7.10
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Author: dependabot[bot]

samples/java/jdbc/pom.xml

@@ -51,7 +51,7 @@
     <dependency>
       <groupId>org.postgresql</groupId>
       <artifactId>postgresql</artifactId>
-      <version>42.7.9</version>
+      <version>42.7.10</version>
     </dependency>
     <dependency>
       <groupId>com.google.cloud</groupId>