Remove some mentions of avconv, following its deprecation.

anntzer · anntzer · commit 16f9be70171c · 2020-02-10T14:17:16.000+01:00
diff --git a/.appveyor.yml b/.appveyor.yml
@@ -81,7 +81,7 @@ test_script:
 
   # this are optional dependencies so that we don't skip so many tests...
   - if x%TEST_ALL% == xyes conda install -q ffmpeg inkscape miktex
-  # missing packages on conda-forge for avconv imagemagick
+  # missing packages on conda-forge for imagemagick
   # This install sometimes failed randomly :-(
   #- choco install imagemagick
 
diff --git a/INSTALL.rst b/INSTALL.rst
@@ -144,8 +144,7 @@ optional Matplotlib backends and the capabilities they provide.
 For better support of animation output format and image file formats, LaTeX,
 etc., you can install the following:
 
-* `ffmpeg <https://www.ffmpeg.org/>`_/`avconv
-  <https://libav.org/avconv.html>`_: for saving movies;
+* `ffmpeg <https://www.ffmpeg.org/>`_: for saving movies;
 * `ImageMagick <https://www.imagemagick.org/script/index.php>`_: for saving
   animated gifs;
 * `LaTeX <https://miktex.org/>`_ and `GhostScript (>=9.0)
