Fix can_push value to false in protected_branch (#2560)

models/branches.go

@@ -26,6 +26,7 @@ type ProtectedBranch struct {
 	ID               int64  `xorm:"pk autoincr"`
 	RepoID           int64  `xorm:"UNIQUE(s)"`
 	BranchName       string `xorm:"UNIQUE(s)"`
+	CanPush          bool   `xorm:"NOT NULL DEFAULT false"`
 	EnableWhitelist  bool
 	WhitelistUserIDs []int64   `xorm:"JSON TEXT"`
 	WhitelistTeamIDs []int64   `xorm:"JSON TEXT"`