Bump maven-pmd-plugin from 3.15.0 to 3.16.0 (apache#92).

Author: garydgregory

src/changes/changes.xml

@@ -87,7 +87,7 @@
         Bump commons-parent from 48 to 52.
      </action>
      <action type="update" dev="ggregory" due-to="Dependabot">
-       Bump maven-pmd-plugin from 3.12.0 to 3.15.0, #44, #54, #67.
+       Bump maven-pmd-plugin from 3.12.0 to 3.16.0, #44, #54, #67, #92.
      </action>
      <action type="update" dev="ggregory" due-to="Dependabot">
        Bump actions/checkout from v2.3.1 to v2.4.0 #46, #72, #78.