fix: update .env.example to run server on heroku (#3531)

* updated .env.example to run server on heroku

* removed trailing slash

Author: Dilshaad21

.env.example

@@ -1,3 +1,3 @@
 GOOGLE_API_KEY="Sample Key"
-API_HOST=http://127.0.0.1:5000
+API_HOST=https://open-event-api-dev.herokuapp.com
 FASTBOOT_DISABLED=true