Simpler method to install Pyzam with ffmpeg

[Luka Filipovic]

You use a Conda environment to install Pyzam with ffmpeg as a dependency.
This makes it easier for users to install the cli tool on their devices.

environment.yml example:

name: pyzam-env
channels:
  - defaults
  - pip
dependencies:
  - ffmpeg
  - pip:
      - pyzam

[Luka Filipovic]

Also add the desktop shortcut for Windows users:

pyzam.exe --speaker --loop