gRPC-Core Release 1.33.1

[Donna Dionne]

This is 1.33.1 (geeky) release announcement for gRPC-Core and the wrapped languages C++, C#, Objective-C, Python, PHP and Ruby. Latest release notes are here.

This release contains refinements, improvements, and bug fixes, with highlights listed below.

Core

• Deprecate GRPC_ARG_HTTP2_MIN_SENT_PING_INTERVAL_WITHOUT_DATA_MS. (#24063)
• Expose Cronet error message to the application layer. (#24083)
• Remove grpc_channel_ping from surface API. (#23894)
• Do not send BDP pings if there is no receive side activity. (#22997)

C++

• Makefile: only support building deps from submodule. (#23957)

C#

• Add trimming attribute to BindServiceMethodAttribute. (#24217)
• Fix incremental build of csproj projects depending on grpc. (#23391)

Python

• [Backport] Make Python 2 an optional dependency for Bazel build. (#24452)
• Allow asyncio API to be imported as grpc.aio. (#24289)
• [gRPC Easy] Fix import errors on Windows. (#24124)
• Make version check for importlib.abc in grpcio-tools more stringent. (#24098)