dep: remove pin on jwcrypto

[jason-famedly]

SYN-44

In #84, the jwcrypto module got bounded to 1.5.6 which is lower than the most current version(1.5.7). This was due to work in that jwcrypto version that hardened the length of the token to a specific value. This interfered with the testing of the Synapse token authenticator, as it creates test token with junk data that do not meet this criteria. This was manifesting as a series of errors that reported:

jwcrypto.common.InvalidJWEKeyLength: Expected key of length 512, got 48

It is currently unknown if this will affect production or only the testing environment. This needs to be checked for/asked about with the relevant parties.

The algorithm tested against is HS512 so I assume that is where the 512 bit requirement comes from. 512 bits * 8bit_per_byte = 64 bytes. That sounds manageable.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.28%. Comparing base (fded967) to head (6230a76).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #87   +/-   ##
=======================================
  Coverage   73.28%   73.28%           
=======================================
  Files           5        5           
  Lines         756      756           
  Branches      145      145           
=======================================
  Hits          554      554           
  Misses        143      143           
  Partials       59       59           

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update fded967...6230a76. Read the comment docs.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[FrenchGithubUser]

Looks good to me!