pin the lower bound for typing-extensions

[liferoad]

Addresses #30513

https://ge.apache.org/s/jifk6hz2rspue/console-log/task/:sdks:python:test-suites:direct:py38:tensorflowInferenceTest?anchor=194&page=1

ImportError: cannot import name 'Buffer' from 'typing_extensions' (/runner/_work/beam/beam/build/gradleenv/1398941892/lib/python3.8/site-packages/typing_extensions.py)

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[tvalentyn]

Started dependency postcommit suite, which might be affected by this change: https://github.com/apache/beam/actions/runs/9276827317

[tvalentyn]

Ah nvm, it shouldn't be affected

[tvalentyn]

waiting for tests to pass

[tvalentyn]

YAML error unrelated: #31429