[Task]: Document guidelines for how version guards should be specified for Beam dependencies

[tvalentyn]

What needs to happen?

We should document this in install_requires and potentially in contributor guide and/or release guide sections of developer docs and have some process that enforces absence of obvious mistakes such as:

• depending on an exact version of a dependency.
• specifying '<=' in upper bound instead of a strict '<'.
• omitting explanations for non-obvious choices, such as a too open or too narrow range.

It might be possible to have a unit test or release validation script that automatically verifies some of that.

Issue Priority

Priority: 2 (default / most normal work should be filed as P2)

Issue Components

• [X] Component: Python SDK
• [ ] Component: Java SDK
• [ ] Component: Go SDK
• [ ] Component: Typescript SDK
• [ ] Component: IO connector
• [ ] Component: Beam examples
• [ ] Component: Beam playground
• [ ] Component: Beam katas
• [ ] Component: Website
• [ ] Component: Spark Runner
• [ ] Component: Flink Runner
• [ ] Component: Samza Runner
• [ ] Component: Twister2 Runner
• [ ] Component: Hazelcast Jet Runner
• [ ] Component: Google Cloud Dataflow Runner

[tvalentyn]

subtask of #25652

[tvalentyn]

related: https://beam.apache.org/contribute/dependencies/

[tvalentyn]

Content (for self reference) https://docs.google.com/document/d/1euZogGjbW4VZNJMFrA5AL1keR5gZO5l45H9b9CoQ0SI/edit