Do not call "git diff" when listing PRs (#33817)

Fix  #31492

modules/structs/pull.go

@@ -27,9 +27,10 @@ type PullRequest struct {
 	Comments                int        `json:"comments"`
 	// number of review comments made on the diff of a PR review (not including comments on commits or issues in a PR)
 	ReviewComments int `json:"review_comments"`
-	Additions      int `json:"additions"`
-	Deletions      int `json:"deletions"`
-	ChangedFiles   int `json:"changed_files"`
+
+	Additions    *int `json:"additions,omitempty"`
+	Deletions    *int `json:"deletions,omitempty"`
+	ChangedFiles *int `json:"changed_files,omitempty"`
 
 	HTMLURL  string `json:"html_url"`
 	DiffURL  string `json:"diff_url"`