Dev dependency declaration file appears in package

> @dsherret, with 0.43.1 the source maps are now gone, but this file still remains:
>
> ```
> npm notice 6.2kB esm/deps/jsr.io/@hexagon/proper-tags/2.0.3-alpha.0/dist/proper-tags.d.ts
> ```
>
> And since it's only a test dependency, it was not supposed to be included in the npm package.
>
> You can easily reproduce this with https://github.com/felipecrs/jsonc-weaver:
>
> ```console
> $ git clone https://github.com/felipecrs/jsonc-weaver
> $ cd jsonc-weaver
> $ deno task build-npm
> $ (cd npm && npm pack)
> ```

_Originally posted by @felipecrs in [#486](https://github.com/denoland/dnt/issues/486#issuecomment-5125483729)_

Reproduce the package contents with the jsonc-weaver commands: deno task build-npm followed by npm pack in the npm directory. Inspect the generated package and the packaging path that includes esm/deps declarations. Done means the test-only proper-tags declaration file is absent from the npm package while the reported build still succeeds.

Written by the indexing model from the issue text.