chore(python): update dependency distlib (#429)

Source-Link: https://github.com/googleapis/synthtool/commit/c4dd5953003d13b239f872d329c3146586bb417e
Post-Processor: gcr.io/cloud-devrel-public-resources/owlbot-python:latest@sha256:ce3c1686bc81145c81dd269bd12c4025c6b275b22d14641358827334fddb1d72

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