hashAlg not set

e.g., passing in `hashAlg` has no effect,
```
const Hash = await require('pure-ipfs-only-hash')
const data = Buffer.from('hello world\n')
hashAlg = 'sha2-256'
cidVersion = 0

await Hash.of(data, {cidVersion, hashAlg})
# 'QmT78zSuBmuS4z925WZfrqQ1qHaJ56DQaTfyMUF7F8ff5o'
# ... but
hashAlg = 'blake2b-8'

await Hash.of(data, {cidVersion, hashAlg})
# 'QmT78zSuBmuS4z925WZfrqQ1qHaJ56DQaTfyMUF7F8ff5o'
```
even though the options object of `ipfs-unixfs-importer` is supported. For example, setting `cidVersion = 1` works as expected.

Should I be using [`js-multiformats`](https://github.com/multiformats/js-multiformats) instead?