chore: replace nyc with c8 for coverage reporting in `package.jso…

…n` (#42)

This pull request includes changes to the `package.json` file to update
the code coverage tool and its dependencies. The most important changes
are:

### Code Coverage Tool Update:

* Replaced `nyc` with `c8` for code coverage reporting in the `coverage`
script. (`package.json`:
[package.jsonL14-R14](diffhunk://#diff-7ae45ad102eab3b6d7e7896acd08c427a9b25b346470d7bc6507b6481575d519L14-R14))

### Dependency Updates:

* Added `c8` as a new dependency. (`package.json`:
[package.jsonR29](diffhunk://#diff-7ae45ad102eab3b6d7e7896acd08c427a9b25b346470d7bc6507b6481575d519R29))
* Removed `nyc` from the list of dependencies. (`package.json`:
[package.jsonL39](diffhunk://#diff-7ae45ad102eab3b6d7e7896acd08c427a9b25b346470d7bc6507b6481575d519L39))