versioning is not correct for go mod

[billykwooten]

Hello! So as of go 1.13 go mod requires semantic versioning for all it's modules including the v in front of the version.

I noticed that the versions released with this are v.0.15.0 for example, with an extra period in-between the v and the semantic version. This breaks go mod completely when trying to pull the required version.

[briandowns]

Thanks for reporting this. I hadn't noticed. This is entirely a mistake on my part. I'll look to see how much activity those tags are getting and if it's minimal, I'll retag them. In the meantime, here's a new tag with your latest changes include. https://github.com/briandowns/openweathermap/releases/tag/v0.16.0

[billykwooten]

No problem, since i'm around this module right now figured i'd bring this up too! Thanks for fixing it! Modules are working with that new tag now.

[briandowns]

Awesome. Thanks for the contributions!