py-JWT: updated to 2.1.0

v2.1.0

Changed
- Allow claims validation without making JWT signature validation mandatory.

Fixed
- Remove padding from JWK test data.
- Make `kty` mandatory in JWK to be compliant with RFC7517.
- Allow JWK without `alg` to be compliant with RFC7517.
- Allow to verify with private key on ECAlgorithm, as well as on Ed25519Algorithm.

Added
- Add caching by default to PyJWKClient
- Add missing exceptions.InvalidKeyError to jwt module __init__ imports
- Add support for ES256K algorithm
- Add `from_jwk()` to Ed25519Algorithm
- Add `to_jwk()` to Ed25519Algorithm
- Export `PyJWK` and `PyJWKSet`

(adam)