Update dependency duplicity to v0.8.22

Author: renovate-bot

requirements.txt

@@ -85,7 +85,7 @@ docker-pycreds==0.4.0
 docutils==0.18.1
 dparse==0.5.1
 dulwich==0.20.26
-duplicity==0.8.12.0
+duplicity==0.8.22
 empy==3.3.4
 entrypoints==0.3
 et-xmlfile==1.1.0