Bump golangci-lint to v2

[smlx]

• Use the v2 import path for installation of the binary.
• Update the arguments passed by nvim-go for v2 compatibility.

Closes: #72

[crispgm]

I think we should compat v1 user or at least tell them to update to v2. Otherwise, they will fail immediately after update.

[smlx]

Do you mean that it should detect the golangci-lint version at runtime and throw an error if the user has v1 installed?

[crispgm]

Do you mean that it should detect the golangci-lint version at runtime and throw an error if the user has v1 installed?

Yes, this would be more compatible.

[smlx]

Does that check improve things? The only problem is that it runs the version check every time you run :GoLint.

[crispgm]

Thanks!