impl Hash for revocation types

[ctz]

This is in support of rustls/rustls#2722.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 26 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.01%. Comparing base (74a40b2) to head (877dbad).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
src/crl/types.rs	0.00%	16 Missing ⚠️
src/signed_data.rs	0.00%	10 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #406      +/-   ##
==========================================
- Coverage   97.57%   97.01%   -0.57%     
==========================================
  Files          20       20              
  Lines        4089     4222     +133     
==========================================
+ Hits         3990     4096     +106     
- Misses         99      126      +27     

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