* feat: new ci for upload coverage data to codecov
Signed-off-by: STRRL <str_ruiling@outlook.com>

* test: do not push code coverage wihtin ci.yml
Signed-off-by: STRRL <str_ruiling@outlook.com>

* chore: update coverage drop threshold
Signed-off-by: STRRL <str_ruiling@outlook.com>

* chore: update for lincense checker
Signed-off-by: STRRL <str_ruiling@outlook.com>

* chore: not specify a certain ref with action/checkout
Signed-off-by: STRRL <str_ruiling@outlook.com>
Co-authored-by: Ti Chi Robot <ti-community-prow-bot@tidb.io>