Add 3.11 to travis ci (#85)

Switch to Ubuntu jammy release, and add 3.11 testing.

.travis.yml

@@ -1,4 +1,4 @@
-dist: focal
+dist: jammy
 language: python
 jobs:
   include:
@@ -10,6 +10,8 @@ jobs:
       env: RUN_PRE_COMMIT=1
     - python: "3.10"
       env: RUN_PRE_COMMIT=0
+    - python: "3.11-dev"
+      env: RUN_PRE_COMMIT=0
 install:
 - pip install -U setuptools pip -r build-requirements.txt
 script: