Fix final formatting issue - add missing newline to project/pom.xml

The integration test XML file was missing a newline at the end,
causing spotless:check to fail. Added the required newline to
make the file compliant with formatting standards.

Author: gnodet

its/core-it-suite/src/test/resources/mng-11133-mixins/project/pom.xml

@@ -36,4 +36,4 @@ under the License.
       <relativePath>../mixins/mixin.xml</relativePath>
     </mixin>
   </mixins>
-</project>
+</project>