Remove tests from npm package to reduce npm package size

[boidolr]

Excluding the tests with the lib/.npmignore file does not work, as can be seen by installing the package.
Adding the exclude pattern to the files section in package.json directly works (tested with npm 8.15.0).
Before:

❯ npm pack
...
npm notice === Tarball Details ===
npm notice name:          nise
npm notice version:       5.1.0
npm notice filename:      nise-5.1.0.tgz
npm notice package size:  276.4 kB
npm notice unpacked size: 1.0 MB
npm notice shasum:        2a9cc94327c00439aa5527ad2a6dcba137225e23
npm notice integrity:     sha512-+tNrmuEAXD0Pe[...]tnsqhCxqbzOfA==
npm notice total files:   23

After:

❯ npm pack
...
npm notice === Tarball Details ===
npm notice name:          nise
npm notice version:       5.1.0
npm notice filename:      nise-5.1.0.tgz
npm notice package size:  255.2 kB
npm notice unpacked size: 853.0 kB
npm notice shasum:        22aee618ad3f5537e0997cf4aa06f9577ff3264a
npm notice integrity:     sha512-Vtxx24zhelAl9[...]UitUs4EGZld/g==
npm notice total files:   16

[fatso83]

Thanks! Good find.

[fatso83]

Published as 5.1.3

[mroderick]

Very nice! Thank you!