Update protos to latest

[andystaples]

Update protobuf definitions to latest

Updates generated protobuf files to the latest
microsoft/durabletask-protobuf
definitions (1caadbd).

Also adds a Copilot agent skill (.github/skills/update-protobuf/SKILL.md)
for regenerating these files in the future, and adds .proto_venv to
.gitignore.

[Copilot]

Pull request overview

Updates Durable Task’s generated Python protobuf bindings to match the latest microsoft/durabletask-protobuf definitions, and adds repo guidance for regenerating these files going forward.

Changes:

• Regenerated orchestrator_service_pb2.py/.pyi from newer proto definitions (adds WorkItemFilters and related filter messages).
• Updated PROTO_SOURCE_COMMIT_HASH to the new upstream source commit.
• Added an agent skill doc for regeneration and ignored the .proto_venv regeneration venv.

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
durabletask/internal/orchestrator_service_pb2.pyi	Updates type stubs to include new workItemFilters and filter message types.
durabletask/internal/orchestrator_service_pb2.py	Updates generated protobuf descriptor / serialized offsets to match latest proto.
durabletask/internal/PROTO_SOURCE_COMMIT_HASH	Points to the new upstream durabletask-protobuf commit hash.
.gitignore	Ignores .proto_venv used for protobuf regeneration.
.github/skills/update-protobuf/SKILL.md	Documents repeatable steps to download proto and regenerate Python outputs.