Mouse Listener: Horizontal Scroll returns change in `dy` (not `dx`)

[asmith26]

Description
When I use a mouse listener and horizontally scroll, the callback returns a change in dy (not dx).

Platform and pynput version
Linux Mint 22 (based on Ubuntu 24.04), pynput==1.7.7

Full conda envinronment.yaml

name: pynput
channels:
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=conda_forge
  - _openmp_mutex=4.5=2_gnu
  - bzip2=1.0.8=h4bc722e_7
  - ca-certificates=2024.7.4=hbcca054_0
  - ld_impl_linux-64=2.40=hf3520f5_7
  - libexpat=2.6.2=h59595ed_0
  - libffi=3.4.2=h7f98852_5
  - libgcc-ng=14.1.0=h77fa898_0
  - libgomp=14.1.0=h77fa898_0
  - libnsl=2.0.1=hd590300_0
  - libsqlite=3.46.0=hde9e2c9_0
  - libuuid=2.38.1=h0b41bf4_0
  - libxcrypt=4.4.36=hd590300_1
  - libzlib=1.3.1=h4ab18f5_1
  - ncurses=6.5=h59595ed_0
  - openssl=3.3.1=hb9d3cd8_3
  - pip=24.2=pyhd8ed1ab_0
  - python=3.12.5=h2ad013b_0_cpython
  - readline=8.2=h8228510_1
  - setuptools=72.2.0=pyhd8ed1ab_0
  - tk=8.6.13=noxft_h4845f30_101
  - tzdata=2024a=h0c530f3_0
  - wheel=0.44.0=pyhd8ed1ab_0
  - xz=5.2.6=h166bdaf_0
  - pip:
      - evdev==1.7.1
      - pynput==1.7.7
      - python-xlib==0.33
      - six==1.16.0

To Reproduce

from pynput import mouse

def on_scroll(x, y, dx, dy):
    print(f"dx={dx}, dy={dy}")

# Collect events until released
with mouse.Listener(on_scroll=on_scroll) as listener:
    listener.join()

I'm finding this prints:

dx=0, dy=1   # when I scroll up (CORRECT)
dx=0, dy=-1  # when I scroll down (CORRECT)
dx=0, dy=1   # when I scroll left (INCORRECT, should be dx=1, dy=0)
dx=0, dy=-1  # when I scroll right (INCORRECT, should be dx=-1, dy=0)

Thanks for any help, and this amazing lib! :)