remove unused property

Author: mtf90

pom.xml

@@ -139,7 +139,6 @@ limitations under the License.
     -->
     <properties>
         <!-- general config -->
-        <deploy-site-github.exec>deploy-site-github</deploy-site-github.exec>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
         <maven.compiler.source>1.8</maven.compiler.source>