Update bitly API usage from the deprecated v3 to v4

[edwinmp]

Simon notified us about this on Slack. Support for v3 ends on January 31.

Resources (suggestion - feel free to find your own)

• https://dev.bitly.com/

[edwinmp]

This has been stalled by dependency updates that are required for it's deploying ... will make time for it.

[ThatcherK]

@edwinmp I remember working on this and finishing it..

[edwinmp]

Yeah ... failed to deploy. Current problem is unrelated to the fix. Its quite annoying really. Don't want to close this till it's deployed.