refactor: remove deprecated typing uses and add custom linter script

[jansegre]

Motivation

I noticed some uses of typing.Set in the code, even after we removing those, because there's no linter it's very easy to forget we can use set instead.

Acceptance Criteria

• add custom linter script to check for deprecated uses of typing

Checklist

• If you are requesting a merge into master, confirm this code is production-ready and can be included in future releases as soon as it gets merged

[codecov]

Codecov Report

Merging #699 (acb0972) into master (3695ad2) will increase coverage by 0.09%.
The diff coverage is 100.00%.

❗ Current head acb0972 differs from pull request most recent head b0672bc. Consider uploading reports for the commit b0672bc to get more accurate results

@@            Coverage Diff             @@
##           master     #699      +/-   ##
==========================================
+ Coverage   84.01%   84.11%   +0.09%     
==========================================
  Files         246      246              
  Lines       20519    20448      -71     
  Branches     2769     2760       -9     
==========================================
- Hits        17240    17200      -40     
+ Misses       2706     2674      -32     
- Partials      573      574       +1     

Impacted Files	Coverage Δ
hathor/consensus/consensus.py	97.82% <100.00%> (-0.05%)	⬇️
hathor/consensus/context.py	100.00% <100.00%> (ø)
hathor/event/websocket/factory.py	92.85% <100.00%> (ø)
hathor/indexes/memory_mempool_tips_index.py	100.00% <100.00%> (ø)
hathor/indexes/memory_tx_group_index.py	93.93% <100.00%> (ø)
hathor/indexes/mempool_tips_index.py	92.38% <100.00%> (ø)
hathor/indexes/tips_index.py	100.00% <100.00%> (ø)
hathor/transaction/storage/cache_storage.py	94.32% <100.00%> (ø)
hathor/websocket/protocol.py	100.00% <100.00%> (ø)

... and 14 files with indirect coverage changes

The base branch was changed.