Add more lock_modes to Repo.fetch_by/3 - #64

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/cache@v3, actions/checkout@v3. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

using commas as separators in "mix do" is deprecated, use + between commands instead

missing specification for function from_ucs4be/1

missing specification for function to_ucs4be/1

missing specification for function is_visible_ascii/1

missing specification for function is_visible_latin1/1

missing specification for function is_iso646_basic/1

missing specification for function is_ascii/1

missing specification for function is_latin1/1

missing specification for function is_bmpchar/1

missing specification for function is_unicode/1

missing specification for function is_iso10646/1