depdencies, core: update Tx-XMPP to be version >= 10.0:

This version changes the package name, so all `wokkel` imports habe been replaced by
`tx_xmpp`

tests/unit/test_plugin_misc_pubsub_contacts.py

@@ -17,7 +17,7 @@
 # along with this program. If not, see <http://www.gnu.org/licenses/>.
 
 from twisted.words.xish import domish
-from wokkel.pubsub import NS_PUBSUB
+from tx_xmpp.pubsub import NS_PUBSUB
 
 from libervia.backend.plugins.plugin_misc_pubsub_contacts import (
     Contact,