fix: restore poll_question entrypoint pointing to xblocks_contrib

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: 2 people

pyproject.toml

@@ -34,6 +34,7 @@ image = "xmodule.template_block:TranslateCustomTagBlock"
 library = "xmodule.library_root_xblock:LibraryRoot"
 library_content = "xmodule.library_content_block:LegacyLibraryContentBlock"
 lti = "xmodule.lti_block:LTIBlock"
+poll_question = "xblocks_contrib:PollBlock"
 problem = "xmodule.capa_block:ProblemBlock"
 randomize = "xmodule.randomize_block:RandomizeBlock"
 sequential = "xmodule.seq_block:SequenceBlock"