feat(epub): Add EPUB support

[0xRaduan]

Addresses #88.

Adds new converter + new test.

[l-lumin]

hi, could you check if this can use existing HtmlConverter

markitdown/src/markitdown/_markitdown.py

Lines 183 to 223 in cb66b35

	class HtmlConverter(DocumentConverter):
	"""Anything with content type text/html"""
	def convert(
	self, local_path: str, **kwargs: Any
	) -> Union[None, DocumentConverterResult]:
	# Bail if not html
	extension = kwargs.get("file_extension", "")
	if extension.lower() not in [".html", ".htm"]:
	return None
	result = None
	with open(local_path, "rt", encoding="utf-8") as fh:
	result = self._convert(fh.read())
	return result
	def _convert(self, html_content: str) -> Union[None, DocumentConverterResult]:
	"""Helper function that converts and HTML string."""
	# Parse the string
	soup = BeautifulSoup(html_content, "html.parser")
	# Remove javascript and style blocks
	for script in soup(["script", "style"]):
	script.extract()
	# Print only the main content
	body_elm = soup.find("body")
	webpage_text = ""
	if body_elm:
	webpage_text = _CustomMarkdownify().convert_soup(body_elm)
	else:
	webpage_text = _CustomMarkdownify().convert_soup(soup)
	assert isinstance(webpage_text, str)
	return DocumentConverterResult(
	title=None if soup.title is None else soup.title.string,
	text_content=webpage_text,
	)

[gagb]

+1

[gagb]

@0xRaduan love this PR. We already have a dependency for HTML to text (markdownify) in the HTML convertor. Can you check if that would be sufficient?