Add Joomla 6 to target platform in update manifests

Update targetplatform version regex from 5.* to (5|6)\..* in both
update.xml and updates.xml so Joomla 6 installations see the
template as a valid update.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

update.xml

@@ -14,7 +14,7 @@
     <downloads>
       <downloadurl type="full" format="zip">https://github.com/mokoconsulting-tech/MokoCassiopeia/archive/refs/tags/v03.06.10.zip</downloadurl>
     </downloads>
-    <targetplatform name="joomla" version="5.*" />
+    <targetplatform name="joomla" version="(5|6)\..*" />
     <maintainer>Moko Consulting</maintainer>
     <maintainerurl>https://mokoconsulting.tech</maintainerurl>
   </update>

updates.xml

@@ -41,6 +41,6 @@
     <maintainer>Moko Consulting</maintainer>
     <maintainerurl>https://mokoconsulting.tech</maintainerurl>
 
-    <targetplatform name='joomla' version='5.*'/>
+    <targetplatform name='joomla' version='(5|6)\..*'/>
   </update>
 </updates>