[GRASS-git] [OSGeo/grass-addons] 71b9b1: r.viewshed.cva: fix if condition syntax warnings

[Markus Neteler]

  Branch: refs/heads/master
  Home:   https://github.com/OSGeo/grass-addons
  Commit: 71b9b1998ced1c97f4de3368b09e50aa1c5ebd4a
      https://github.com/OSGeo/grass-addons/commit/71b9b1998ced1c97f4de3368b09e50aa1c5ebd4a
  Author: Markus Neteler <neteler at gmail.com>
  Date:   2020-08-02 (Sun, 02 Aug 2020)

  Changed paths:
    M grass7/raster/r.viewshed.cva/r.viewshed.cva.py

  Log Message:
  -----------
  r.viewshed.cva: fix if condition syntax warnings

fixes `SyntaxWarning: "is not" with a literal. Did you mean "!="?`