It is filled with the same value as in the corresponding `date` column.

All the timestamps included only time information to the hour-level.
This patch makes it use the full capabilities of milliseconds.

Makes sense specifically in the context when exercising date/time
conversions from `TIMESTAMP` to corresponding Python types in the
future.

`datetime.date.today()` returns the current local date. In order to
reduce test flakyness when comparing UTC-based datetimes with localtime-
based variants, `datetime.utcnow().date()` is a better choice.

Use that canonical command line for advertising the installation of the
CrateDB Python driver::

    $ pip install "crate[sqlalchemy]" --upgrade

The idea is to show the user right away how to install the driver
together with its SQLAlchemy dialect extension.

The other way round, it will be missed by people more often than not,
causing general confusion and poor experience on the first time of use.

It is intended for developer folks in general, so it is perfectly fine
to tell them about the canonical `pip` incantation, including all the
possible options and parameters, which has the highest chance to be
copied verbatim into the terminal without further ado. This even holds
true for non-developer folks.

On the "nightly" runs, the test suite did not actually use CrateDB
nightly builds, but used the version defined in `versions.cfg` instead.

See https://docs.github.com/en/actions/using-jobs/using-concurrency
Should reduce the resource usage a bit and may speed up things.

… problems

Reference: #451

CrateDB does not produce nightly tarballs for macOS.

Since CrateDB 3.0.0 already, it would have been correct to use the `information_schema.key_column_usage.table_schema` column instead of
`table_catalog` (mostly contains value `doc`, the default schema of
CrateDB). Now, with CrateDB >=5.1.0, `table_catalog` will always return
`crate`, thus the need for a fix.