feat!: remove packlink

They don't have API docs available and, according to their support, don't support API integrations anymore. The API requests always return "Bad Request" without any possibility to fix them.

README.md

@@ -1,12 +1,12 @@
 ## ERPNext Shipping
 
 A Shipping Integration for ERPNext with various platforms. Platforms integrated in this app are:
-- [Packlink](https://www.packlink.com/en-GB/)
+
 - [LetMeShip](https://www.letmeship.com/en/)
 - [SendCloud](https://www.sendcloud.com/home-new/)
 
 ## Features
-- Creation of shipment to a carrier service (e.g. FedEx, UPS) via LetMeShip, Packlink, and SendCloud. 
+- Creation of shipment to a carrier service (e.g. FedEx, UPS) via LetMeShip and SendCloud. 
 - Compare shipping rates. 
 - Printing the shipping label is also made available within the Shipment doctype.
 - Templates for the parcel dimensions.
@@ -27,8 +27,6 @@ For the compare shipping rates feature to work as expected, you need to generate
 
 ![LetMeShip 2020-08-05 09-54-28](https://user-images.githubusercontent.com/17470909/89377411-500c4f80-d724-11ea-8fe5-b11fec2a5c27.png)
 
-![Packlink 2020-08-05 09-53-47](https://user-images.githubusercontent.com/17470909/89377423-56023080-d724-11ea-8396-fb9f60a0d581.png)
-
 ### Fetch Shipping Rates
 ![core2](https://user-images.githubusercontent.com/17470909/89377460-70d4a500-d724-11ea-8550-a2813b936651.gif)