feat: support sub-issue

Author: e7217

github/github.go

@@ -222,6 +222,7 @@ type Client struct {
 	Search             *SearchService
 	SecretScanning     *SecretScanningService
 	SecurityAdvisories *SecurityAdvisoriesService
+	SubIssue           *SubIssueService
 	Teams              *TeamsService
 	Users              *UsersService
 }
@@ -458,6 +459,7 @@ func (c *Client) initialize() {
 	c.Search = (*SearchService)(&c.common)
 	c.SecretScanning = (*SecretScanningService)(&c.common)
 	c.SecurityAdvisories = (*SecurityAdvisoriesService)(&c.common)
+	c.SubIssue = (*SubIssueService)(&c.common)
 	c.Teams = (*TeamsService)(&c.common)
 	c.Users = (*UsersService)(&c.common)
 }