fix(config): fix npmignore config

[skjnldsv]

Fix #560

$ npm pack 
npm notice 
npm notice 📦  @nextcloud/l10n@2.0.0
npm notice === Tarball Contents ===
npm notice 1.9kB  CHANGELOG.md
npm notice 35.1kB LICENSE
npm notice 2.3kB  README.md
npm notice 748B   dist/date.d.ts
npm notice 1.4kB  dist/gettext.d.ts
npm notice 3.0kB  dist/gettext.js
npm notice 3.0kB  dist/gettext.mjs
npm notice 428B   dist/index.d.ts
npm notice 16.0kB dist/index.js
npm notice 15.7kB dist/index.mjs
npm notice 1.2kB  dist/registry.d.ts
npm notice 2.7kB  dist/translation.d.ts
npm notice 1.8kB  package.json
npm notice === Tarball Details ===