github: modify pull request template (#6314)
github: modify pull request template (#6314)

Signed-off-by: Rustin-Liu <c7d168847ad25898cad3ce2d480246882ded574b@gmail.com>
BusyJay/tikv,BusyJay/tikv,pingcap/tikv,c4pt0r/tikv,pingcap/tikv,BusyJay/tikv,BusyJay/tikv