message: Add snapshot repo
diff: <!-- jhipster-needle-maven-property -->
  </properties>
  + <repositories>
  + <!-- TODO To remove after final JHipster 6 release -->
  + <repository>
  + <id>oss.sonatype.org-snapshot</id>
  + <url>http://oss.sonatype.org/content/repositories/snapshots</url>
  + <releases>
  + <enabled>false</enabled>
  + </releases>
  + <snapshots>
  + <enabled>true</enabled>
  + </snapshots>
  + </repository>
  + <!-- jhipster-needle-maven-repository -->
  + </repositories>
  +
  <dependencyManagement>
  <dependencies>
  <dependency>
  