enhancement/bug: electric version falls back to 0.0.0 when used as hex package

[itoxiq]

When adding electric to an existing elixir project its version will be set to 0.0.0, due to the functions(load from env or from package.json which is not included in hex package) in the mix.exs.

This can lead to the following:

Unchecked dependencies for environment dev:
* electric (Hex package)
  the dependency does not match the requirement "~> 1.0.0-beta.1", got "0.0.0"
** (Mix) Can't continue due to errors on dependencies

one can maybe provide the version again via an env var - but this is unintuitive and also repetitive 😅