Missing package versions on conda-forge make some versions of grpcio unusable

[apmorton]

Solution to issue cannot be found in the documentation.

• I checked the documentation.

Issue

Because grpcio-tools specifically pins the matching grpcio version and many versions of this package were not published to conda-forge, any version of grpcio>1.46.0 and <1.51.1 is unusable if you also need grpcio-tools.

Installed packages

channels:
  - conda-forge
  - nodefaults
dependencies:
  - grpcio-tools
  - grpcio==1.49.1

Environment info

Could not solve for environment specs
Encountered problems while solving:
  - package grpcio-tools-1.33.2-py39h58526e2_0 requires grpcio 1.33.2, but none of the providers can be installed

[timkpaine]

@conda-forge/core if conda will pin grpc 1.58, grpcio-tools should also exist for 1.58

[apmorton]

It seems like this changed in 1.52.0 - #23

This package now specifies a minimum version - which may also be incorrect as grpcio specifies a run_exports: https://github.com/conda-forge/grpc-cpp-feedstock/blob/main/recipe/meta.yaml#L45

I believe this package should simply not specify a runtime dependency on grpcio and let the run_exports take over.