Sigstore

* Added client configuration message for signing ([277](https://github.com/sigstore/protobuf-specs/pull/277))
* Added a new format for the media type that is compatible with OCI registries ([279](https://github.com/sigstore/protobuf-specs/pull/279))
* Added events.proto for Ruby package ([264](https://github.com/sigstore/protobuf-specs/pull/264))
* Targeted Node16 for Typescript package ([230](https://github.com/sigstore/protobuf-specs/pull/230))

Changed

* Docs: Removed timestamp from checkpoint ([247](https://github.com/sigstore/protobuf-specs/pull/247))
* Remove EXPERIMENTAL prefix from LMS schemes ([214](https://github.com/sigstore/protobuf-specs/pull/214))

Fixed

* Docs: Clarified trust anchor in chain ([245]([https://github.com/sigstore/protobuf-specs/pull/210](https://github.com/sigstore/protobuf-specs/pull/245))

* Options for more generic observer time ([179](https://github.com/sigstore/protobuf-specs/pull/179))
* **BREAKING**: `VerificationMaterials.contents` now has an additional `certificate` variant,
which is preferred in `0.3` bundles with the Sigstore PGI ([191](https://github.com/sigstore/protobuf-specs/pull/191))
* Added algorithm registry documentation and updated `PublicKeyDetails` message
([194](https://github.com/sigstore/protobuf-specs/pull/194), [#212](https://github.com/sigstore/protobuf-specs/pull/212))
* Deterministic ECDSA is **deprecated**
* NIST-P384 and NIST-P521 curves **added**
* Existing (and underspecified) RSA key types are
**deprecated**. New RSA keytypes are defined that specifies size
of public modulus and hash algorithm. RSA now only supports
[PKCS1](https://datatracker.ietf.org/doc/html/rfc8017#section-8.2)
signature scheme, and PKIX
([SubjectPublicKeyInfo](https://datatracker.ietf.org/doc/html/rfc5280#section-4.1))
encoding.
* Experimental support for
[LMS](https://datatracker.ietf.org/doc/html/rfc8554) key types.

Changed

* Deprecated support for detached SCTs ([188](https://github.com/sigstore/protobuf-specs/pull/188))

Fixed

* Docs: Clarified rotation of verification materials in the trust root
([210](https://github.com/sigstore/protobuf-specs/pull/210)

Added

* CloudEvents proto for Rekor pub/sub messages ([86](https://github.com/sigstore/protobuf-specs/pull/86))
* Generate jsonschema ([112](https://github.com/sigstore/protobuf-specs/pull/112))
* Rust bindings for jsonschema ([118](https://github.com/sigstore/protobuf-specs/pull/118))
* Dependabot to update dependencies ([99](https://github.com/sigstore/protobuf-specs/pull/99))

Changed

There were no changes in this release.

Fixed

* Docs: Fixed spelling error ([97](https://github.com/sigstore/protobuf-specs/pull/97))
* Docs: Clarified log index vs global log index ([101](https://github.com/sigstore/protobuf-specs/pull/101))
* Docs: Clarified purpose of SET as a signed timestamp ([100](https://github.com/sigstore/protobuf-specs/pull/100))
* Docs: Clarify message digest purpose ([114](https://github.com/sigstore/protobuf-specs/pull/114))

Removed

There were no removals in this release.