Remove asynctest. (#934)

Author: janiversen

requirements.txt

@@ -58,7 +58,6 @@ sphinx-rtd-theme
 # development, everything needed to develop/test/check.
 # -------------------------------------------------------------------
 # install:development]
-asynctest==0.13.0
 bandit==1.7.4
 black==22.3.0
 codespell==2.1.0