Upgrade grpcio version

[maryamziaa]

Proposed change(s)

Describe the changes made in this PR.
Upgrade grpcio Python binary wheels since grpcio 1.48.2 doesn't come with precompiled binaries to be used with Apple M1. Ref: grpc/grpc#34821 (comment)

Useful links (Github issues, JIRA tickets, ML-Agents forum threads etc.)

Types of change(s)

• Bug fix
• New feature
• Code refactor
• Breaking change
• Documentation update
• Other (please describe): Update grpcio library version in setup.py

Checklist

• Added tests that prove my fix is effective or that my feature works
• Updated the changelog (if applicable)
• Updated the documentation (if applicable)
• Updated the migration guide (if applicable)

Other comments

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All committers have signed the CLA.

[Copilot]

Pull Request Overview

This PR updates the grpcio dependency version to support Apple M1 machines by expanding the upper version limit and removes outdated OS X installation instructions for grpc.

• Update grpcio version range to <=1.51.3 in ml-agents/setup.py and ml-agents-envs/setup.py
• Remove obsolete OS X GRPC library installation instructions from docs/Installation.md

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
ml-agents/setup.py	Updated grpcio dependency version range for Apple M1 support
ml-agents-envs/setup.py	Synced grpcio dependency version update
docs/Installation.md	Removed outdated OS X GRPC installation instructions

Comments suppressed due to low confidence (1)

docs/Installation.md:167

• The removal of the manual GRPC installation instructions is appropriate given the updated grpcio wheels; however, consider referencing this change in the upgrade notes or documentation to guide users upgrading from previous versions.

#### (OS X) Installing GRPC libraries [removed block]