I had change dist to jammy in .travis.yml, but travis still build by foca

I had change dist to jammy in .travis.yml, but travis still build by focal. Why this happen? How to solve?

log as below:
Build system information
Build language: python
Build group: edge
Build dist: jammy
Build id: 273820197
Job id: 629649297
Runtime kernel version: 5.4.0-1021-aws
VM: default
travis-build version: 6b157a1c
Build image provisioning date and time
Tue 18 Aug 2020 12:55:32 PM UTC
Operating System Details
Distributor ID: Ubuntu
Description: Ubuntu 20.04 LTS
Release: 20.04
Codename: focal

Thank you!