Bump spring-boot-starter-web in /plugins/maven/example-client (#200)

Bumps [spring-boot-starter-web](https://github.com/spring-projects/spring-boot) from 2.2.6.RELEASE to 2.3.1.RELEASE.
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](https://github.com/spring-projects/spring-boot/compare/v2.2.6.RELEASE...v2.3.1.RELEASE)
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Co-authored-by: Ndependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

plugins/maven/example-client/pom.xml

@@ -88,7 +88,7 @@
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-web</artifactId>
-            <version>2.2.6.RELEASE</version>
+            <version>2.3.1.RELEASE</version>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>