Fix typo in awful.wallpaper doc example

[elig0n]

[Aire-One]

Looks like anongit.freedesktop.org is down again.

[Aire-One]

It seems we cannot retry the pipelines more than twice (3 total runs). anongit.freedesktop.org have to be fixed since other pipelines can successfully download the deps. @elig0n can you rebase the PR to make the pipeline restart?

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 48.41%. Comparing base (2b7006f) to head (896837e).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3958      +/-   ##
==========================================
- Coverage   48.53%   48.41%   -0.12%     
==========================================
  Files         196      195       -1     
  Lines       22437    22421      -16     
==========================================
- Hits        10889    10856      -33     
- Misses      11548    11565      +17     

see 3 files with indirect coverage changes