Allow Windows drives in filename

This allows the colon (:) in the drive specifier on Windows to be included into the filepath match.

Author: vidartf

src/pytest_mypy_testing/message.py

@@ -74,7 +74,7 @@ class Message:
  )
 
  OUTPUT_RE = re.compile(
- r"^(?P<fname>[^:]+):"
+ r"^(?P<fname>([a-zA-Z]:)?[^:]+):"
  r"(?P<lineno>[0-9]+):"
  r"((?P<colno>[0-9]+):)?"
  r" *(?P<severity>(error|note|warning)):"