fix: Fix regular expression for Sphinx inventory parsing

Some Sphinx inventories don't match
the `sphinx_item_regex` defined in `InventoryItem`.
Allowing any number of whitespace characters at the end
instead of requiring at least one fixes this issue.

Co-authored-by: Luis Michaelis <luis.michaelis@iee.fraunhofer.de>
Issue #496: #496
PR #497: #497

src/mkdocstrings/inventory.py

@@ -46,7 +46,7 @@ def format_sphinx(self) -> str:
             uri = uri[: -len(self.name)] + "$"
         return f"{self.name} {self.domain}:{self.role} {self.priority} {uri} {dispname}"
 
-    sphinx_item_regex = re.compile(r"^(.+?)\s+(\S+):(\S+)\s+(-?\d+)\s+(\S+)\s+(.*)$")
+    sphinx_item_regex = re.compile(r"^(.+?)\s+(\S+):(\S+)\s+(-?\d+)\s+(\S+)\s*(.*)$")
 
     @classmethod
     def parse_sphinx(cls, line: str) -> "InventoryItem":