Add `version.json` to match go-multihash

[sumanjeet0012]

go-multihash has a version.json file. py-multihash should have one for consistency across the multiformats ecosystem.

Problem

go-multihash includes:

{
  "version": "v0.2.3"
}

py-multihash does not have this file.

Proposed Solution

1. Create version.json:

   {
     "version": "v3.0.0"
   }

2. Add to bump-my-version config in pyproject.toml.

Related

• Go equivalent: go-multihash version.json