Self updating arkade binary

[yankeexe]

There's an option to get arkade's latest release from arkade itself. But since the binary PATH is ~/.arkade/bin and it tries to overwrite itself while updating it shows text file busy.

Image for reference

Expected Behaviour

arkade updates itself when downloading new version.

Current Behaviour

Shows text file is busy

Possible Solution

Use something like these to update arkade itself:

1. https://github.com/sanbornm/go-selfupdate
2. https://github.com/minio/selfupdate

Steps to Reproduce (for bugs)

arkade get arkade

Are you a GitHub Sponsor (Yes/No?)

Check at: https://github.com/sponsors/alexellis

• [ ] Yes
• [x] No

[yankeexe]

@alexellis what do you think about this? I can work on it if it seems like a viable addition.