fix: Parse Deprecated sections without version info in Google-style d…

…ocstrings

Griffe requires a version indicator in Google-style Deprecated sections.
If no such indicator is found, then the user is warned, and *then* the
section **is silently dropped**.

[As a proponent of readable docstrings][1], [and apparently in spirit
with the Google style guide][2], I consider it unacceptable to drop
information from a docstring just because it is not properly formatted
as data.

In this patch, I propose parsing the section without an associated
version number instead, and using the section's text as its... well,
text.

[1]: mkdocstrings/python#166 (comment) '"the source form of the docstring should be readable"'
[2]: google/styleguide#117 (comment)  '"Docstrings are meant for human consumption, please keep them readable for us humans. :)"'

Issue-352: #352

src/_griffe/docstrings/google.py

@@ -709,7 +709,10 @@ def _read_deprecated_section(
         version, text = text.split(":", 1)
     except ValueError:
         docstring_warning(docstring, new_offset, f"Could not parse version, text at line {offset}")
-        return None, new_offset
+        return (
+            DocstringSectionDeprecated(version="", text=text),
+            new_offset,
+        )
 
     version = version.lstrip()
     description = text.lstrip()