Remove ExtensionMetadata import

Signed-off-by: Liran Funaro <liran.funaro@gmail.com>

Author: liran-funaro

sphinx_markdown_builder/__init__.py

@@ -2,16 +2,14 @@
 A Sphinx extension to add markdown generation support.
 """
 
-from sphinx.util.typing import ExtensionMetadata
-
 from sphinx_markdown_builder.builder import MarkdownBuilder
 
 
 __version__ = "0.6.9"
 __docformat__ = "reStructuredText"
 
 
-def setup(app) -> ExtensionMetadata:
+def setup(app):
     app.add_builder(MarkdownBuilder)
     app.add_config_value("markdown_http_base", "", "html", str)
     app.add_config_value("markdown_uri_doc_suffix", ".md", "html", str)