Update travis

jedymatt · jedymatt · commit 75888d58e0c2 · 2021-08-08T21:59:47.000+08:00
diff --git a/.travis.yml b/.travis.yml
@@ -4,7 +4,10 @@ python:
     - "3.7"
     - "3.8"
     - "3.9"
-
+os:
+    - linux
+    - osx
+    - windows
 before_install:
     - py -m pip install --upgrade pip
 
