Made RTD apt install FFMPEG instead of installing a Python binding (#1896)

* Try to apt install ffmpeg instead

* remove symlink

* try

.readthedocs.yml

@@ -3,6 +3,7 @@ build:
   image: latest
   apt_packages:
     - libpango1.0-dev
+    - ffmpeg
 python:
    version: 3.8
    install:

docs/rtd-requirements.txt

@@ -1,2 +1 @@
-imageio-ffmpeg
 jupyterlab

docs/source/conf.py

@@ -20,20 +20,6 @@ import manim
 sys.path.insert(0, os.path.abspath("."))
 
 
-if os.environ.get("READTHEDOCS") == "True":
-    site_path = get_python_lib()
-    # we need to add ffmpeg to the path
-    ffmpeg_path = os.path.join(site_path, "imageio_ffmpeg", "binaries")
-    # the included binary is named ffmpeg-linux..., create a symlink
-    [ffmpeg_bin] = [
-        file for file in os.listdir(ffmpeg_path) if file.startswith("ffmpeg-")
-    ]
-    os.symlink(
-        os.path.join(ffmpeg_path, ffmpeg_bin), os.path.join(ffmpeg_path, "ffmpeg")
-    )
-    os.environ["PATH"] += os.pathsep + ffmpeg_path
-
-
 # -- Project information -----------------------------------------------------
 
 project = "Manim"