@rollup/plugin-babel incorrectly listed as direct dependency

[tbazin]

Description Following commit https://github.com/djipco/webmidi/commit/ac627227584db82d1f113ced98b247b4ed3ec87f, @rollup/plugin-babel is listed as a direct dependency rather than a devDependency. This causes installation warnings or errors depending on the package manager used. For instance, using pnpm:

 ERR_PNPM_PEER_DEP_ISSUES  Unmet peer dependencies
.
└─┬ webmidi
  └─┬ @rollup/plugin-babel
    ├── ✕ missing peer rollup@^1.20.0||^2.0.0
    ├── ✕ missing peer @babel/core@^7.0.0
    └─┬ @rollup/pluginutils
      └── ✕ missing peer rollup@^1.20.0||^2.0.0
Peer dependencies that should be installed:
  @babel/core@^7.0.0                          rollup@">=1.20.0 <2.0.0 || >=2.0.0 <3.0.0"

This is easily fixed by moving it back to the devDependencies.

[djipco]

Yes, this makes a lot of sense. I'm not sure why it ended up in the dependencies. I'll merge it. Thanks for contributing.