0.3.0 does not depend on `jupyterlite-core`

## Description

This does not have PEP 621 dependencies on `jupyterlite-javascript-kernel`

## Reproduce

Given:
```yaml
# environment.yml
channels: [conda-forge]
dependencies:
- python
- pip
- pip:
- jupyterlite-javascript-kernel
```

Then
```bash
mamba upgrade --file environment.yml --prefix .venv
source activate .venv
pip list | grep jupyter
```
See:
```
jupyterlite_javascript_kernel 0.3.0
```

## Expected behavior

```
jupyter_core x.x.x
jupyterlite-core 0.3.0
jupyterlite_javascript_kernel 0.3.0
```

## Context

- https://github.com/conda-forge/jupyterlite-core-feedstock/issues/22
- https://github.com/conda-forge/staged-recipes/pull/26440

Start with the dependency declarations using the PEP 621 metadata referenced in the issue, then reproduce the environment.yml installation with the provided mamba and pip commands. Done means installing jupyterlite-javascript-kernel 0.3.0 also installs jupyterlite-core 0.3.0, matching the expected package list.

Written by the indexing model from the issue text.