build(deps-dev): bump org.springframework.boot:spring-boot

Bumps [org.springframework.boot:spring-boot](https://github.com/spring-projects/spring-boot) from 4.0.3 to 4.0.6.
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v4.0.3...v4.0.6)

---
updated-dependencies:
- dependency-name: org.springframework.boot:spring-boot
  dependency-version: 4.0.6
  dependency-type: direct:development
...

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

Author: dependabot[bot]

java-spanner-jdbc/samples/quickperf/pom.xml

@@ -79,7 +79,7 @@
     <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot</artifactId>
-      <version>4.0.3</version>
+      <version>4.0.6</version>
       <scope>test</scope>
     </dependency>
     <dependency>