Gardening: Provide version for build-helper-maven-plugin.

Change-Id: I99063cb8a48682ed23fe3b82079b6409fc548309
Reviewed-on: https://review.couchbase.org/c/couchbase-jvm-clients/+/213277
Tested-by: Build Bot <[email protected]>
Reviewed-by: David Nault <[email protected]>

Author: mikereiche

osgi-feature/pom.xml

@@ -113,6 +113,7 @@
             <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>build-helper-maven-plugin</artifactId>
+                <version>${build-helper-maven-plugin.version}</version>
                 <executions>
                     <execution>
                         <id>attach-artifacts</id>