e2e_subs: Remove unused Python cryptography package

[michaeldiamant]

Removes an unused e2e_subs Python dependency: https://pypi.org/project/cryptography.

[algorandskiy]

It's unclear to me how pip resolves cryptography

https://github.com/graingert/cryptograpy/blob/default/cryptograpy.py

this is an empty package, so maybe we do not need cryptography at all? All git grep cryptography entries are irrelevant.

[codecov]

Codecov Report

Merging #4939 (ae8303b) into master (5363ae7) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4939      +/-   ##
==========================================
- Coverage   53.51%   53.50%   -0.01%     
==========================================
  Files         432      432              
  Lines       53624    53624              
==========================================
- Hits        28697    28693       -4     
  Misses      22701    22701              
- Partials     2226     2230       +4     

Impacted Files	Coverage Δ
crypto/merkletrie/trie.go	66.42% <0.00%> (-2.19%)	⬇️
crypto/merkletrie/node.go	91.62% <0.00%> (-1.87%)	⬇️
catchup/service.go	69.08% <0.00%> (-1.45%)	⬇️
catchup/peerSelector.go	98.95% <0.00%> (-1.05%)	⬇️
data/transactions/verify/txn.go	73.72% <0.00%> (-0.85%)	⬇️
ledger/acctupdates.go	69.24% <0.00%> (-0.25%)	⬇️
ledger/tracker.go	78.90% <0.00%> (+0.84%)	⬆️
network/wsPeer.go	68.97% <0.00%> (+1.90%)	⬆️
ledger/blockqueue.go	88.50% <0.00%> (+2.87%)	⬆️

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[michaeldiamant]

we do not need cryptography at all?

@algorandskiy Thanks for raising the question. I think you're right - The package is not used. I've updated the PR accordingly.