refine camel to dash conversion

Author: rmorshea

src/idom/utils.py

@@ -312,8 +312,8 @@ def _vdom_attr_to_html_str(key: str, value: Any) -> tuple[str, str]:
     elif key.startswith("data") or key.startswith("aria"):
         # Handle data-* attribute names
         key = _CAMEL_CASE_SUB_PATTERN.sub("-", key)
-    else:
-        key = _CAMEL_TO_DASH_CASE_HTML_ATTRS.get(key, key)
+    elif key in _CAMEL_TO_DASH_CASE_HTML_ATTRS:
+        key = _CAMEL_TO_DASH_CASE_HTML_ATTRS[key]
 
     assert not callable(
         value