This reverts commit 66d8ef1ad9d5952b7e7f026658f71aafc861950e, reversing
changes made to 6a8359f3d3be01af6f5b124b61af7ee1c77c17d0.

The `--with` option was added in Bundler 1.10 but in this case it
shouldn't even be needed: I've tested the original command locally and
the pg gem was installed, so I believe the user that opened the original
MR ran the wrong command (i.e. `sudo -u git -H bundle install --without
development test postgres --deployment` instead of `sudo -u git -H bundle
install --without development test mysql --deployment`.

See discussion at
https://gitlab.com/gitlab-org/gitlab-ce/commit/66d8ef1ad9d5952b7e7f026658f71aafc861950e
for more context.

Update patch_versions.md with explicit --with statement for db gem group

## What does this MR do?
Updates `patch_versions.md`'s instructions on installing gems to explicitly install either the postgres or mysql groups.

## Are there points in the code the reviewer needs to double check?
No, but thank you for your time.

## Why was this MR needed?
I performed the steps listed in `patch_versions.md` and ran the command for updating postgres gems. Bundler told me at the end that it had not installed the postgres gem group, which caused the next step, migrating the DB, to fail for obvious reasons.

Changing the command to `--with postgres` made it install the postgres gem group, and db:migrate then passed.

## What are the relevant issue numbers?
None

## Screenshots (if relevant)
N/A

See merge request !3955

Prepend letter v to GitLab Workhorse version numbers

This helps to address gitlab-org/gitlab-ce#12684 so as to maintain consistency in all GitLab projects.

It also addresses: https://gitlab.com/gitlab-org/gitlab-workhorse/issues/4

Next Steps

- create a set of duplicate tags in workhorse to prevent errors when updating from the patch guide


See merge request !3088