[misc] Allow more commits in changelog generation (#6115)
[misc] Allow more commits in changelog generation (#6115)

### Brief Summary

There are more than 200 commits in v1.1.3
(https://github.com/taichi-dev/taichi/releases/tag/v1.1.3) so let's
increase the number of commits for changelog generation.
yuanming-hu/taichi,yuanming-hu/taichi,yuanming-hu/taichi,yuanming-hu/taichi