added new formatters

html_to_django/formatters/attr_formatter.py

@@ -0,0 +1,8 @@
+from bs4 import BeautifulSoup
+
+
+def format(soup: BeautifulSoup) -> None:
+    for element in soup.find_all(attrs={"dj-attr": True}):
+        tag, value = element.get("dj-attr").split(";")
+        element[tag] = f"{{{{ {value} }}}}"
+        del element.attrs["dj-attr"]