core, dependencies: Update Tx-XMPP to 0.12:

Tx-XMPP 0.12 has beaking change in `discoFeature.identities` because it now supports
`xml:lang` attribute, so this update implies updating the code everywhere were this is
used.

tests/unit/test_component_pubsub.py

@@ -777,9 +777,7 @@ class TestPubsubResourceItems:
             subscriptionTo=False,
             subscriptionFrom=True,
         )
-        mock_xep_0356.get_roster = AsyncMock(
-            return_value={requestor_jid: roster_item}
-        )
+        mock_xep_0356.get_roster = AsyncMock(return_value={requestor_jid: roster_item})
         host.plugins["XEP-0356"] = mock_xep_0356
 
         with raises(StanzaError, match="forbidden"):
@@ -814,9 +812,7 @@ class TestPubsubResourceItems:
             subscriptionTo=False,
             subscriptionFrom=True,
         )
-        mock_xep_0356.get_roster = AsyncMock(
-            return_value={requestor_jid: roster_item}
-        )
+        mock_xep_0356.get_roster = AsyncMock(return_value={requestor_jid: roster_item})
 
         await resource._items(request)
 
@@ -1478,6 +1474,6 @@ class TestPubsubAutoSubscribe:
         call_args = host.memory.storage.get_pep_last_items.call_args
         # We want the second positional argument (list of publishers)
         publishers_arg = call_args[0][1]
-        assert publishers_arg == [requestor_jid], (
-            f"Expected only self-subscription, got {publishers_arg}"
-        )
+        assert publishers_arg == [
+            requestor_jid
+        ], f"Expected only self-subscription, got {publishers_arg}"