Upgrade pywebpush to 1.5.0

[Chris-V]

Description:

This version includes a fix for the serialization errors that occurred
when updating push subscriptions.

Changes since version 1.3.0:
web-push-libs/pywebpush@1.3.0...28d2b55

Related issue (if applicable):
fixes #10751
fixes #11024

Example entry for configuration.yaml (if applicable):

notify:
  - name: NOTIFIER_NAME
    platform: html5
    gcm_api_key: 'gcm-server-key'
    gcm_sender_id: 'gcm-sender-id'

Checklist:

• The code change is tested and works locally.

If the code communicates with devices, web services, or third-party tools:

• Local tests with tox run successfully. Your PR cannot be merged unless tests pass
• New dependencies have been added to the REQUIREMENTS variable (example).
• New dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.

[balloob]

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