Features
* Added support for protos in conformance tests.
* Added a cel-spec go module.
Tests
* AND / OR error handling
* Macro equivalence
* Mixed type comparison
* `has` macro tests on maps, proto2, and proto3
* Empty proto fields, single-field proto literals
* Unicode strings
Fixes
* Fix bad quoting in the conformance tests
* Namespace tests split into their own suite
* Document JSON conversion
* Fixed nested `protobuf.Any` comparisons.