RFC 1123 date format fix

[bambriz]

Description

This fixes an issue with non-English locales making non-RFC 1123 Date formats. This fix makes it into an RFC 1123 Date format regardless of the locale. See Issue 29109

All SDK Contribution checklist:

• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

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• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

Testing Guidelines

• Pull request includes test coverage for the included changes.

[azure-sdk]

API change check

API changes are not detected in this pull request.

[simorenoh]

Question, why are we re-inventing the wheel here? Is there no existing native package we can use? I'd think we would want to avoid any manual parsing or creating of day/month abbreviations if we don't exclusively need them.

[bambriz]

Question, why are we re-inventing the wheel here? Is there no existing native package we can use? I'd think we would want to avoid any manual parsing or creating of day/month abbreviations if we don't exclusively need them.

Changed to use email.utils formatdate.

[simorenoh]

/azp run python - cosmos - tests

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[simorenoh]

LGTM thanks Bryan - seems like we will have to disable the pkdelete test while we update the subscription being used for our pipeline test account. I'll make an issue for that and assign you to it.

[bambriz]

/azp run python - cosmos - tests

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).