minor fix in build script

Author: clausnagel

build.gradle

@@ -44,7 +44,7 @@ javadoc {
         header = "$project.name $project.version"
         bottom """
             <a target="_blank" href="https://github.com/xmlobjects/xml-objects/issues">Report a bug or suggest an enhancement</a><br />
-            ${project.name} is open source and licensed under the <a target="_blank" href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a><br />
+            ${project.name} is open source and licensed under the <a target="_blank" href="https://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a><br />
             Official website and more information at: <a target="_blank" href="https://github.com/xmlobjects">https://github.com/xmlobjects</a><br />
             Copyright &copy; 2013-${date.format('yyyy')}<br />
             Claus Nagel &lt;[email protected]&gt;