Any way to load contents of a local .env inside the runner setup?

I was wondering if instead of passing env vars individually I can just point to a local `.env`?

```lua
require('nvim-test.runners.jest'):setup {
...
env = { CUSTOM_VAR = 'value' }, -- can we load `/.env` here instead?
...
}
```

Loving nvim-test btw. Thank you so much for putting it together!

Start at the nvim-test.runners.jest setup entry point shown in the issue and inspect how the env table is consumed when configuring a runner. Determine the project-supported scope for loading a local .env file and define completion by covering that behavior without requiring individual environment-variable entries.

Written by the indexing model from the issue text.