Bump checkstyle from 8.41.1 to 8.42 (#358)

Bumps [checkstyle](https://github.com/checkstyle/checkstyle) from 8.41.1 to 8.42.
- [Release notes](https://github.com/checkstyle/checkstyle/releases)
- [Commits](checkstyle/checkstyle@checkstyle-8.41.1...checkstyle-8.42)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

cloud-spanner-spring-data-r2dbc/pom.xml

@@ -252,7 +252,7 @@
           <dependency>
             <groupId>com.puppycrawl.tools</groupId>
             <artifactId>checkstyle</artifactId>
-            <version>8.41.1</version>
+            <version>8.42</version>
           </dependency>
         </dependencies>
         <executions>