Release v3 - change v2 suffix to v3

[sylwiaszunejko]

Because of recent changes there is a need for a new major release. Changes are switching to scylladb/gocql and replacing Unsafe with Strict mechanism.

[sylwiaszunejko]

I have a problem with cmd/schemagen. I cannot use v3 there (e.g. in cmd/schemagen/testdata/go.mod) because release is not done yet. And because I changed module name in go.mod I had to add github.com/scylladb/gocqlx/v2 v2.8.0 to requirements to use v2 in cmd/schemagen. I am not sure how to do it better.
Now there will be a need for a second PR after the release to remove github.com/scylladb/gocqlx/v2 v2.8.0 from requirements and to change v2 to v3 in cmd/schemagen

[dkropachev]

@sylwiaszunejko , I have pushed commit that solves problem with schemagen, please take a look.

[sylwiaszunejko]

@dkropachev I don't know why but when I tried github.com/scylladb/gocqlx/v3 v3.0.0 in schemagen go.mod tests failed. Now it seems to work, maybe I did something wrong in the code

[dkropachev]

Please don't forget to tag it when it is merged, or before the merge.

[dkropachev]

@dkropachev I don't know why but when I tried github.com/scylladb/gocqlx/v3 v3.0.0 in schemagen go.mod tests failed. Now it seems to work, maybe I did something wrong in the code

It is my bad, on last PR to schemagen I have introduced test that actually compiles code from the test.
But I have missed the fact that it uses gocqlx as a external library, while it should be replaced with content from file system.
And it did not work for you because v3 is not yet published

[sylwiaszunejko]

Please don't forget to tag it when it is merged, or before the merge.

I thought the correct steps were:

1. merge this PR
2. create a tag
3. create a release from tag

Correct me if I am wrong

[sylwiaszunejko]

I thought the correct steps were:

1. merge this PR
2. create a tag
3. create a release from tag

@mmatczuk Could you have a look at the PR? and confirm if I am right about steps for release?

[sylwiaszunejko]

@roydahan could you look at this?

[roydahan]

Looks fine to me.
We will need to highlight it in the release notes.