Depend on betterproto2 runtime instead of the compiler

[merlimat]

Problem

pyproject.toml lists betterproto2-compiler as a runtime dependency. It is only the protoc plugin used by gen-proto.sh (--python_betterproto2_out); the code under src/ imports just betterproto2. As a result, everyone who installs oxia also gets ruff, jinja2, markupsafe and strenum.

Example

dependencies = [
    "betterproto2-compiler",
    "grpcio",
    "xxhash",
]

Runtime closure (uv export --no-dev) before: betterproto2, betterproto2-compiler, grpcio, jinja2, markupsafe, python-dateutil, ruff, six, strenum, typing-extensions, xxhash.

Change

dependencies = [
    # Generated stubs call betterproto2.check_compiler_version(), which requires
    # the runtime major.minor to match the betterproto2-compiler that produced them.
    "betterproto2>=0.9.0,<0.10",
    "grpcio",
    "xxhash",
]

[dependency-groups]
dev = [
    "betterproto2-compiler>=0.9.0",
    ...
]

The <0.10 upper bound is required: the generated stubs pin _COMPILER_VERSION = "0.9.0" and betterproto2.check_compiler_version() raises at import time unless the runtime major.minor matches. The compiler in the dev group needs no upper bound, since betterproto2-compiler 0.9.0 itself requires betterproto2>=0.9.0,<0.10.

Runtime closure after: betterproto2, grpcio, python-dateutil, six, typing-extensions, xxhash.

The uv.lock diff covers only the dependency move. Plain uv lock also rewrites the header requires-python = ">=3.13" to >=3.10 (the lock body already holds the 3.10 resolution); that unrelated line is left out.

Testing

• uv run --frozen pytest: 68 passed.
• With dev dependencies removed (uv sync --no-dev), import oxia and the generated proto module both work, and neither the compiler nor ruff is installed.
• Regenerating stubs with the dev-group compiler matches the committed stubs except for the two intentional hand edits (get_sequence_updates and get_notifications return the cancellable call). Note: gen-proto.sh currently has to be run from src/, since its paths predate the move under src/; that's a separate fix.