fix: import GenerateICS function from calendar in email.js to resolve ReferenceError

src/helpers/email.js

@@ -5,7 +5,7 @@ const path = require('path');
 const { MailtrapClient } = require("mailtrap");
 const nodemailer = require("nodemailer");
 const CON = require("./const");
-const CAL = require("./calendar");
+const { GenerateICS } = require("./calendar");
 const common = require("./common");
 const Handlebars = require('handlebars');