remove redundant dependencies

[brualan]

I use this tool all the time. As well as a large number of gophers around the world. Therefore, I thought that reducing the number of dependencies would be a very useful step for the development of this project. That's why:

1. Faster installation, by reducing the number of network requests to get dependencies. On the cheapest VPS, the original goweight was installed in 31.402s, mine in 8.363s. This is almost 4x acceleration
2. Barely noticeable acceleration of startup by reducing the size of the executable file. It's almost imperceptible in a single run, but small wins add up to big wins when the tool is run hundreds of times every day by thousands of people around the world.
3. Reproducibility of builds and user safety. Over time, projects are abandoned, APIs change, github may be unavailable, and sometimes developer accounts are hacked to embed malicious functionality into library code. When we are not dependent on third-party solutions, we can be more confident that the project can be compiled without fear of "infection" and / or problems with the inaccessibility of something.

Binary size reduction on amd64 linux: 5848 B -> 3028 B

P.S. I would like to further develop and support goweight, which has not seen a release since May 2019. Assigning me as a maintainer will greatly help me improve the quality of the project and add more features to it. thanks

[brualan]

@jondot Hi, just a reminder 😉

[brualan]

@jondot Just a reminder

[brualan]

@jondot Hi, just a reminder wink 😉

[brualan]

@jondot
Hi, I hope that you will see this PR some day. It's been 5 month since it's opening. Please do something (merge, comment, reject) about it. I really like this tool and use it almost every day, as many other developers do. And hope that this PR will make it better. So please let's make open source software better for all of us and keep creating new more challenging things.