Revert MR 306 except poetry lock change

See merge request !308

This reverts commit 9e1fc957.

This reverts commit ee6f3c81.

This reverts commit f10f33f3.

This reverts commit 86e257d3.

This reverts commit b4ce9b7a.

This reverts commit 50d75f13.

Replace geomagio/Metadata.py & Poetry Update

See merge request !306

Revert v1.9.4 changes

See merge request !305

V1.9.4

See merge request !304

V1.9.3

See merge request !303

Update version info in code.json and pyproject.toml

See merge request !302

Update FGE offsets for HON, GUA, BDT.

See merge request !301

Fix custom json encoder in pydantic+fastapi

See merge request !300

Pydantic v1's json module contain[s|ed] a dictionary called `ENCODERS_BY_TYPE`
that was commonly used to overide default json encoders. Pydantic v2 is moving
away from this to a "better" system. FastAPI attempted to stay compatible with
both v1 and v2 by pulling ENCODERS_BY_TYPE into their own codebase, but this
broke our custom type `UTCDateTime`, at least for anything using fastapi.

We thought we fixed this with a recent MR, but it turns out all we did was
fix the validator. We did not fix the encoder itself. So, validation steps
would pass, but we continued to server malformed json for UTCDateTimes. This
commit reverts to the earlier version of pydantic_utcdatetime.py, and adds a
small kluge that modifies `ENCODERS_BY_TYPE` in both pydantic and fastapi.

Update .gitlab-ci.yml file

See merge request !299

Documentation Update Feb2024

See merge request !297

...but don't actually update (`poetry lock --no-update`).

Python version >=3.10 don't need to use the typing module types imported
(e.g., `from typing import List, Tuple`), but if we continue to stick with
these, geomag-algorithms should be backward compatible to py3.8. Some day
we'll have to bump up our minimum python version, but not today.