Remove tests from npm package to reduce npm package size

[boidolr]

Removing the tests (and GitHub workflows) from the package by only including the root files reduces the package file by about half (tested with npm 9.8.0). Before:

❯ npm pack
...
npm notice === Tarball Details ===
npm notice name:          fastq
npm notice version:       1.15.0
npm notice filename:      fastq-1.15.0.tgz
npm notice package size:  8.6 kB
npm notice unpacked size: 39.4 kB
npm notice shasum:        95987241d4b02262d717bf1d57df7542a4e5ad8d
npm notice integrity:     sha512-JewKD7kBsuCx1[...]1kZVl0dlXgXFQ==
npm notice total files:   14

After:

❯ npm pack
...
npm notice === Tarball Details ===
npm notice name:          fastq
npm notice version:       1.15.0
npm notice filename:      fastq-1.15.0.tgz
npm notice package size:  5.5 kB
npm notice unpacked size: 19.2 kB
npm notice shasum:        943cf41058968f769c197f547381b0a108836290
npm notice integrity:     sha512-lBOEBRXpJXBdJ[...]YcOvc5TaizdbA==
npm notice total files:   8

Resolves #46