Add python 3.9 to CI

.circleci/config.yml

@@ -42,6 +42,11 @@ jobs:
       - image: python:3.8-slim
     <<: *test-template
 
+  py39:
+    docker:
+      - image: python:3.9-slim
+    <<: *test-template
+
   package-and-publish:
     machine: true
     working_directory: ~/Buku
@@ -99,6 +104,7 @@ workflows:
       - py36
       - py37
       - py38
+      - py39
 
   nightly:
     triggers: