List transitive Python SDK dependencies in base_image_requirements.txt for SDK container.

Beam has a list of dependencies (listed in setup.py). These are Beam's direct dependency. Each of these direct dependency will have their own list of dependencies. These are transitive dependencies of Beam. Beam depends on them indirectly and in setup.py Beam does not list them.

In a worker environment it is beneficial to lock version of all Beam dependencies including the indirect ones.