Closes #595.

No longer run by default, and leaves the environment fouled.

Closes #636.

```
RefreshError: ("Failed to ... from the Google Compute Enginemetadata service. Status: 403 ...)
```

Closes #920.

* chore: update .repo-metadata.json

* remove api_shortname

* revert

Test types under CI using new 'mypy' nox session.

Co-authored-by: arithmetic1728 <[email protected]>

These `ValueError`s can be raised by `google.auth.jwt.decode` e.g.:

* https://github.com/googleapis/google-auth-library-python/blob/8f1e9cfd56dbaae0dff64499e1d0cf55abc5b97e/google/oauth2/id_token.py#L162
* https://github.com/googleapis/google-auth-library-python/blob/8f1e9cfd56dbaae0dff64499e1d0cf55abc5b97e/google/oauth2/id_token.py#L135
* https://github.com/googleapis/google-auth-library-python/blob/8f1e9cfd56dbaae0dff64499e1d0cf55abc5b97e/google/auth/jwt.py#L255

Handling of this is noted in the user docs [1]

[1] https://developers.google.com/identity/sign-in/web/backend-auth

Co-authored-by: arithmetic1728 <[email protected]>

* chore(python): update release.sh to use keystore

Source-Link: googleapis/synthtool@69fda12
Post-Processor: gcr.io/cloud-devrel-public-resources/owlbot-python:latest@sha256:ae600f36b6bc972b368367b6f83a1d91ec2c82a4a116b383d67d547c56fe6de3

* use urllib3 instead of requests.packages.urllib3

* lint

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

* feat: add api key support

* chore: update

* Update google/auth/_default.py

Co-authored-by: Bu Sun Kim <[email protected]>

Co-authored-by: Bu Sun Kim <[email protected]>

* fix(deps): allow cachetools 5.0 for python 3.7+

Changes listed https://github.com/tkem/cachetools/blob/master/CHANGELOG.rst#v500-2021-12-21

* chore: remove split pin

* Update setup.py

* 🦉 Updates from OwlBot

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>
Co-authored-by: arithmetic1728 <[email protected]>

🤖 I have created a release *beep* *boop*
---


## [2.4.0](v2.3.3...v2.4.0) (2022-01-20)


### Features

* add 'py.typed' declaration ([#919](#919)) ([c993504](c993504))
* add api key support ([#826](#826)) ([3b15092](3b15092))


### Bug Fixes

* **deps:** allow cachetools 5.0 for python 3.7+ ([#937](#937)) ([1eae37d](1eae37d))
* fix the message format for metadata server exception ([#916](#916)) ([e756f08](e756f08))


### Documentation

* fix intersphinx link for 'requests-oauthlib' ([#921](#921)) ([967be4f](967be4f))
* note ValueError in `verify_oauth2_token` ([#928](#928)) ([82bc5f0](82bc5f0))

---
This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).