fix(gomod): getting dep name with no version

[sangheee]

Changes

Fixed getting a name with no version when doing a go mod update.

Context

There is a process that compares depName and depName with no version. and when getting depName with no version from depName, It only can handle the depName that has three elements separated by '/'. It causes some problems like described below:

- gomodules.xyz/jsonpatch/v2 v2.2.0
+ gomodules.xyz/jsonpatch/v2/v3 v3.0.1

It should upgrade like gomodules.xyz/jsonpatch/v3 v3.0.1.

Also, Handling the depName containing gopkg.in/ is duplication because it is handled below. https://github.com/renovatebot/renovate/blob/55898f85ae2f1c727ae0478a059b5c392ccc9c51/lib/modules/manager/gomod/update.ts#L97-L101

Documentation (please check one with an [x])

• [ ] I have updated the documentation, or
• [X] No documentation update is required

How I've tested my work (please select one)

I have verified these changes via:

• [ ] Code inspection only, or
• [x] Newly added/modified unit tests, or
• [ ] No unit tests but ran on a real repository, or
• [ ] Both unit tests + ran on a real repository

[JamieMagee]

Can you add a test to prevent regression please?

[sangheee]

@JamieMagee added :)

[rarkins]

@sangheee as you haven't granted maintainer edit permissions, we can't update this branch or fix any of the problems. Please reopen with "Maintainers can edit" permissions.