flutter升级遇到的问题：
Your flutter checkout has local changes that would be erased by upgrading. If
you want to keep these changes, it is recommended that you stash them via "git
stash" or else commit the changes to a local branch. If it is okay to remove
local changes, then re-run this command with --force.
根据最后一句提示：
终端：flutter upgrade --force
