Bump spring-webmvc in /Spring.gb/lesson6/dbase-web

Bumps [spring-webmvc](https://github.com/spring-projects/spring-framework) from 4.3.13.RELEASE to 5.3.18.
- [Release notes](https://github.com/spring-projects/spring-framework/releases)
- [Commits](spring-projects/spring-framework@v4.3.13.RELEASE...v5.3.18)

---
updated-dependencies:
- dependency-name: org.springframework:spring-webmvc
  dependency-type: direct:production
...

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

Author: dependabot[bot]

Spring.gb/lesson6/dbase-web/pom.xml

@@ -9,7 +9,7 @@
 
   <properties>
     <java-version>1.8</java-version>
-    <spring.version>5.3.15.RELEASE</spring.version>
+    <spring.version>5.3.18</spring.version>
     <hibernate.version>5.2.12.Final</hibernate.version>
     <failOnMissingWebXml>false</failOnMissingWebXml>
   </properties>