Allow supplying Authorization: via query parameter.

There is no other way to authorize GitHub and Gogs webhook payloads.

src/pages.go

@@ -174,6 +174,13 @@ func postPage(w http.ResponseWriter, r *http.Request) error {
 		}
 		allowRepoURL = fmt.Sprintf(config.Wildcard.CloneURL, userName, repoName)
 	} else {
+		// GitHub and Gogs cannot supply an `Authorization:` header.
+		if r.Header.Get("Authorization") == "" {
+			if value := r.URL.Query().Get("Authorization"); value != "" {
+				r.Header.Set("Authorization", value)
+			}
+		}
+
 		if err := Authorize(w, r); err != nil {
 			return err
 		}