Merge pull request bryanyang0528#115 from bryanyang0528/add_python10

add python 3.10

Author: bryanyang0528

.travis.yml

@@ -1,9 +1,13 @@
 language: python
-python:
-  - "3.6"
-  - "3.7.13"
-  - "3.8"
-  - "3.9"  
+matrix:
+  fast_finish: true
+  include:
+    - python:  '3.10.2'
+      dist:  bionic
+    - python:  '3.9'
+    - python:  '3.8'
+    - python:  '3.7.13'
+
 # command to install dependencies
 install:
   - pip install .[dev]