Replace opencv dependency with headless version

Signed-off-by: Jacob Stopak <jacob@initialcommit.io>

Author: initialcommit-io

README.md

@@ -64,8 +64,6 @@ $ git-sim <subcommand> -h
 * Python 3.7 or greater
 * Pip (Package manager for Python)
 * [Manim (Community version)](https://www.manim.community/)
-* GitPython
-* OpenCV
 
 ## Commands
 Basic usage is similar to Git itself - `git-sim` takes a familiar set of subcommands including "log", "status", "add", "restore", "commit", "stash", "branch", "tag", "reset", "revert", "merge", "rebase", "cherry-pick", along with corresponding options.

setup.py

@@ -22,7 +22,7 @@
     install_requires=[
         'gitpython',
         'manim',
-        'opencv-python',
+        'opencv-python-headless',
     ],
     keywords='git sim simulation simulate git-simulate git-simulation git-sim manim animation gitanimation image video dryrun dry-run',
     project_urls={