Add driver for pgx v5

[treuherz]

Fixes #827

• Move existing driver into database/pgx/v4
• Make exported items into database/pgx into links to database/pgx/v4, marked as Deprecated
• Mark defunct ErrDatabaseDirty as Deprecated - no code returns it
• Bump pgx/v4 dependency
• Add test runs for newer Postgres versions

If you'd like the last couple of changes to be broken into a different PR then let me know.

[coveralls]

Coverage: 58.526%. Remained the same when pulling 1ecd0a871e4c4bbb61165ed550a7a5c3463c47f1 on treuherz:feature/pgxv5 into 8ec04221b49d69b123b39b9bc9b81774ee5b760e on golang-migrate:master.

[koenbollen]

Hey! Quick bump from me? I'm currently running this branch to allow me to use pgx and golang-migrate together. (thanks btw!)

Any updates on getting this merged? 😇

[treuherz]

Rebased on top of master

[mprimeaux]

Any updates on getting this merged? Appreciate everyone's time.

[pmorelli92]

Please some prio 🙏

[franchb]

Any updates on this PR please?

[MNovruzov]

Any updates please???

[mprimeaux]

Hi @dhui. Would you mind reviewing and consider an approval? We have quite a few platforms waiting for this PR to be merged. Your help, and the help of any maintainer, is greatly appreciated.

[treuherz]

Rebased on top of master again to fix conflicts, and bumped pgx minor versions again.

@vincentdaniel it was nice of you to approve this last time, but it didn't look like that granted mergeability, is that correct?

[vincentdaniel]

@treuherz correct, I am not maintainer of the project but I tried my luck anyway to see 🙈

[treuherz]

Implemented comments, rebased on master again to resolve go.mod conflicts.

[kriswill]

can we merge/release this?