Add "algorithm mismatch" error to improve jws

[ghost]

Upstream libraries that depend on jws.verify() break when the upstream keys contain a mixed set of algorithms. This is a nominal occurance for OIDC servers and should be properly handled.

[codecov]

Codecov Report

Merging #304 (546e96c) into master (96474ec) will decrease coverage by 0.11%.
The diff coverage is 84.00%.

❗ Current head 546e96c differs from pull request most recent head 1ce256e. Consider uploading reports for the commit 1ce256e to get more accurate results

@@ Coverage Diff @@## master #304 +/- ##
==========================================
- Coverage 92.94% 92.83% -0.12% 
==========================================
Files 15 15 Lines 1418 1423 +5 ==========================================
+ Hits 1318 1321 +3 - Misses 100 102 +2 

Impacted Files	Coverage Δ
jose/jws.py	93.54% <60.00%> (-1.50%)	⬇️
jose/backends/cryptography_backend.py	93.18% <77.77%> (ø)
jose/backends/ecdsa_backend.py	97.50% <100.00%> (ø)
jose/backends/native.py	97.56% <100.00%> (ø)
jose/backends/rsa_backend.py	95.62% <100.00%> (ø)
jose/exceptions.py	100.00% <100.00%> (ø)

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[ghost]

As mentioned in the issue, this implements step 2 of Appendix D of the JWS spec

2. Filter the set of collected keys. For instance, some
   applications will use only keys referenced by "kid" (key ID) or
   "x5t" (X.509 certificate SHA-1 thumbprint) parameters. If the
   application uses the JWK "alg" (algorithm), "use" (public key
   use), or "key_ops" (key operations) parameters, keys with
   inappropriate values of those parameters would be excluded.
   Additionally, keys might be filtered to include or exclude keys
   with certain other member values in an application-specific
   manner. For some applications, no filtering will be applied.

[dimaqq]

@mpdavis given that the original PR author account is deleted, maybe it's time to make a call: either take this PR over, maybe add more tests and merge it, or close it if it's incomplete?

My 2c: this PR is a good start.

[berislavlopac]

Do we have any updates on this PR? I currently have this issue in a set up that wraps jose in several layers so it's difficult to work around it. :(