fix: add CORS access header

gcf_sheets_api.go

@@ -64,7 +64,9 @@ func getSheetData(sheet *RawSheetData) string {
 
 // Create JSON response from sheet data
 func httpResponse(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Access-Control-Allow-Origin", "*");
 	w.Header().Set("Content-Type", "application/json");
+
 	fmt.Fprint(w, getSheetData(sheetDataToStruct()))
 }