fix(api): Use latest bs4 syntax for declaring parser

src/api/src/create_book/parser.py

@@ -16,8 +16,7 @@ def clean_tree(title: str, id: int, body: str) -> BeautifulSoup:
     <h1 class="chapter-title" id={id}>{title}</h1>
     <section class="chapter-body"></section>
 """,
-        parser="html.parser",  # head/body tags aren't generated
-        features="lxml",
+        features="html.parser",  # head/body tags aren't generated
     )
 
     insert_at = cast(Tag, new_soup.find("section"))