Update spring-boot-maven-plugin to 2.1.5.RELEASE

Change-Id: If16a72a1270eb57bc1fb27b18b8c396453dbbe60
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

pom.xml

@@ -421,7 +421,7 @@
         <plugin>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-maven-plugin</artifactId>
-          <version>2.1.2.RELEASE</version>
+          <version>2.1.5.RELEASE</version>
         </plugin>
       </plugins>
     </pluginManagement>