Reduce package size

[homer0]

What does this PR do?

The .npmignore wasn't ignoring a lot of unnecessary stuff.

BEFORE:

npm notice === Tarball Details ===
npm notice name:          @homer0/prettier-plugin-jsdoc
npm notice version:       7.0.0
npm notice filename:      @homer0/prettier-plugin-jsdoc-7.0.0.tgz
npm notice package size:  276.0 kB
npm notice unpacked size: 2.5 MB
npm notice shasum:        3242da8e32aa1499540f4ebbc8e2bc7cf314a2ca
npm notice integrity:     sha512-wl9dnXGE2gfIC[...]Fdhv9nEzozT7A==
npm notice total files:   244

AFTER:

npm notice === Tarball Details ===
npm notice name:          @homer0/prettier-plugin-jsdoc
npm notice version:       7.0.0
npm notice filename:      @homer0/prettier-plugin-jsdoc-7.0.0.tgz
npm notice package size:  43.5 kB
npm notice unpacked size: 181.2 kB
npm notice shasum:        593e516b783083296f26c7e9e5c6572dc8b859a9
npm notice integrity:     sha512-tFP2eSxiyx6EH[...]vewG0rFUZQNFA==
npm notice total files:   35

How should it be tested manually?

npm pack

[github-actions]

🎉 This PR is included in version 7.0.2 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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