manim: fix

Turns out that O and 0 are different characters, even though they look
the same in many monospace fonts (including mine). Unfortunately, they
look very different to grep -F...

pkgs/applications/video/manim/default.nix

···
       python3 manim.py example_scenes.py $scene -l
       tail -n 20 files/Tex/*.log  # Print potential LaTeX erorrs
       ${file}/bin/file videos/example_scenes/480p15/$scene.mp4 \
-        | tee | grep -F "ISO Media, MP4 Base Media v1 [IS0 14496-12:2003]"
+        | tee | grep -F "ISO Media, MP4 Base Media v1 [ISO 14496-12:2003]"
     done
   '';