Revert "Removed < 1.66 for grpcio"

[liferoad]

Reverts #34196

The go tests (https://github.com/apache/beam/actions/runs/15907748034/workflow) are still stuck:

https://github.com/apache/beam/actions/runs/15907748034/job/44867028781

https://github.com/apache/beam/actions/runs/15908913599/job/44870989192

[github-actions]

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R: @claudevdm for label python.

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