Cardano Updates

Compilation fails with serde 1.0.157
https://github.com/serde-rs/serde/issues/2415
Removing empty serde annotation fixes the issue

In this PR:

- Started using Poetry for dep management
- Added import snapshot command but still missing some parts of the
workflow:
- Couldn't test it with the working snapshot_tool (field names will
probably change)
   - Couldn't get dreps from GVC API

I'm opening this as it is to be able to work on other stuff while I
figure out the missing parts.

PS: I'll rename the tool in a future PR (it's not only ideascale
importer anymore).

---------

Co-authored-by: Sasha Prokhorenko <[email protected]>

This should be a backward-compatible revision of the DB Schema used for
Vit-SS but expanded to handle general elections, not just funds.

The election-db crate is intended to be self contained, such that DB
logic is only contained in this crate.
The crate does not handle migrations, but it does check if the db schema
it was built against is correct with respect to the db schema in the
database,

This schema is only intended to work on postgres, but it is intended in
future that this crate may actually create a generic election
information data source, so that we could retrieve this data from
multiple data sources (web 2 and web 3) without changing the consuming
code.

`config_table.rs` is intentionally incomplete. It is an example of how
the db operations should be encapsulated fully internally to this crate.
It will be completed in a further round of work to this crate, and not
this PR.

There is a test to ensure the schema validation works, but its not great
and I am open to suggestions of how we test it in CICD.
It checks if the schema known to the crate has been fully applied to the
connected DB.
Tests we would need to fully test it:
1. Test all combinations of db connection strings, env vars, and ,env
files work as expected (Valid, invalid and not set). Also needs to test
that Parameter has priority over env var which has priority over the
.env file. And that when an error is returned, its meaningful and
sensible.
2. Test that when the migrations are only partially applied, that is
detected and an error returned listing the missing migrations.
3. Test that when an unknown migration is applied to the db, that an
error is returned listing the unknown migrations.
4. A combination of 2 & 3.

ps. Given the nature of this PR, I made this a draft so it can have a
full round of review, and approval will not auto merge. But its not a
draft, other than the notes above, it should be complete. I will merge
when reviews are complete.