bpo-20392: Fix inconsistency with uppercase file extensions in mimetypes.guess_type (GH-30229)

(cherry picked from commit 5dd7ec52b83e7f239774cf7478106fcc7b0a36f3)

Co-authored-by: Kumar Aditya <59607654+kumaraditya303@users.noreply.github.com>
3 files changed