Bump org.postgresql:postgresql in /samples/spring-ai-agent

Bumps [org.postgresql:postgresql](https://github.com/pgjdbc/pgjdbc) from 42.7.5 to 42.7.7.
- [Release notes](https://github.com/pgjdbc/pgjdbc/releases)
- [Changelog](https://github.com/pgjdbc/pgjdbc/blob/master/CHANGELOG.md)
- [Commits](pgjdbc/pgjdbc@REL42.7.5...REL42.7.7)

---
updated-dependencies:
- dependency-name: org.postgresql:postgresql
  dependency-version: 42.7.7
  dependency-type: direct:production
...

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

Author: dependabot[bot]

samples/spring-ai-agent/pom.xml

@@ -29,7 +29,7 @@
     <properties>
         <java.version>21</java.version>
         <spring-ai.version>1.0.0</spring-ai.version>
-        <postgresql.version>42.7.5</postgresql.version>
+        <postgresql.version>42.7.7</postgresql.version>
         <jib-maven-plugin.version>3.4.5</jib-maven-plugin.version>
         <testcontainers.version>1.21.1</testcontainers.version>
     </properties>