chore: remove 'pip install' statements from python_library templates [autoapprove] (#424)

Source-Link: https://github.com/googleapis/synthtool/commit/1f37ce74cbc4897f35c9ba5c40393b102da913b1
Post-Processor: gcr.io/cloud-devrel-public-resources/owlbot-python:latest@sha256:8e84e0e0d71a0d681668461bba02c9e1394c785f31a10ae3470660235b673086

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>
7 files changed