Remove -m option from grpcio-tool install command on Linux

[n-jay]

Link the issue(s) this pull request is related to. https://github.com/AcademySoftwareFoundation/opencue.io/issues/256

Summarize your change. Updated the gRPC installation command on Linux.

The earlier command included a -m option that resulted in an error.

[linux-foundation-easycla[bot]]

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• :white_check_mark: login: n-jay / name: Nuwan Jayawardene (8abaf112315cdc927150b4c1c81d56d5ecedd5f7)