Fix CI rot

ci/azure-pipelines.yml

@@ -156,7 +156,7 @@
   pool:
     vmImage: windows-2019
   variables:
-    interpreter: C:\hostedtoolcache\windows\Python\3.7.7\x64\python.exe
+    interpreter: C:\hostedtoolcache\windows\Python\3.7.8\x64\python.exe
     target: x86_64-pc-windows-msvc
   steps:
   - task: UsePythonVersion@0

test/requirements.txt

 arrow
 dataclasses;python_version<"3.7"
 numpy;platform_machine=="x86_64" and python_version<"3.9"
-pendulum;sys_platform!="win" and python_version<"3.9" and platform_machine=="x86_64"
+pendulum;sys_platform=="linux" and python_version<"3.9" and platform_machine=="x86_64"
 psutil
 pytest
 pytz