Installing cfnspec shows the coverage directory is being published to npm. I assume this should be excluded since build artifacts aren't typically published, and at a glance most CDK packages exclude any build artifacts from the published package. (If there is a specific reason why the coverage folder is being published, please advise since I'd be interested to understand the use case.)

```
$ npm install @aws-cdk/cfnspec
$ ls -1 node_modules/@aws-cdk/cfnspec/
CHANGELOG.md
LICENSE
coverage
lib
package.json
...
$  ls -1 node_modules/@aws-cdk/cfnspec/coverage
base.css
block-navigation.js
build-tools
favicon.png
index.html
junit.xml
...
```
----

### All Submissions:

* [x] Have you followed the guidelines in our [Contributing guide?](https://github.com/aws/aws-cdk/blob/master/CONTRIBUTING.md)

### Adding new Unconventional Dependencies:

* N/A

### New Features

* N/A

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

(cherry picked from commit f15b18a)

…#20931)

This is an automatic backport of pull request #20016 done by [Mergify](https://mergify.com).


---


<details>
<summary>Mergify commands and options</summary>

<br />

More conditions and actions can be found in the [documentation](https://docs.mergify.com/).

You can also trigger Mergify actions by commenting on this pull request:

- `@Mergifyio refresh` will re-evaluate the rules
- `@Mergifyio rebase` will rebase this PR on its base branch
- `@Mergifyio update` will merge the base branch into this PR
- `@Mergifyio backport <destination>` will backport this PR on `<destination>` branch

Additionally, on Mergify [dashboard](https://dashboard.mergify.com/) you can:

- look at your merge queues
- generate the Mergify configuration with the config editor.

Finally, you can contact us on https://mergify.com
</details>

…) (aws#20931)

This is an automatic backport of pull request aws#20016 done by [Mergify](https://mergify.com).


---


<details>
<summary>Mergify commands and options</summary>

<br />

More conditions and actions can be found in the [documentation](https://docs.mergify.com/).

You can also trigger Mergify actions by commenting on this pull request:

- `@Mergifyio refresh` will re-evaluate the rules
- `@Mergifyio rebase` will rebase this PR on its base branch
- `@Mergifyio update` will merge the base branch into this PR
- `@Mergifyio backport <destination>` will backport this PR on `<destination>` branch

Additionally, on Mergify [dashboard](https://dashboard.mergify.com/) you can:

- look at your merge queues
- generate the Mergify configuration with the config editor.

Finally, you can contact us on https://mergify.com
</details>