Fix django-channels import

`django-channels` module has only dist files which are built with
parcel. This leads to `assignment to undeclared variable parcelRequire`
error.

A simple workaround is to add `var parcelRequire;` to the beginning of
the module.

front/vite.config.js

@@ -3,11 +3,21 @@
 import { defineConfig } from 'vite'
 import { createVuePlugin as vue } from "vite-plugin-vue2";
 
-const path = require("path");
+import path from 'path'
 
 // https://vitejs.dev/config/
 export default defineConfig({
-  plugins: [vue()],
+  plugins: [
+    vue(),
+    {
+      name: 'fix-django-channels',
+      transform (src, id) {
+        if (id.includes('django-channels')) {
+          return `var parcelRequire;${src}`
+        }
+      }
+    }
+  ],
   resolve: {
     alias: {
       "@": path.resolve(__dirname, "./src"),