[workflow] enforce PR title format by GitHub Acions/workflows

[archibate]

Concisely describe the proposed feature
As mentioned in #1153, I merged a PR without a tag by accident: Fix "unclosed file" in "ti regression" (#1147).
It would be great if we could enforce PR to be tagged & first-word-uppercase by GitHub workflow.

Describe the solution you'd like (if any)
Add a job to .github/workflow/persubmit.yml. If someone is expert on GitHub Actions, please go ahead :)

Additional comments
About PR title rules, please see https://taichi.readthedocs.io/en/latest/contributor_guide.html#prtag

[yuanming-hu]

Great proposal. We should also enforce: if there are more than two tags, there should be exactly one space between different tags. E.g. [Lang] [ir].

Note that the uppercase condition should only be enforced when the first character is a letter (a-z, A-Z).