[Bitbucket]: PR: Edit fails

[jeremyfiel]

Describe the bug
When editing a PR summary, the update fails with the following error

EDIT: This also happens when editing the title of the PR

To Reproduce
Steps to reproduce the behavior:

1. Open an existing PR
2. Edit the summary
3. Click Save
4. See error

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A side note: the api call being used here is using BASIC auth. Can this be upgraded to use Bearer token?

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Expected behavior

I should be able to edit the summary successfully.

Screenshots
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Environment and Version (please complete the following information):

• Atlassian Plugin Version (3.4.6)
• Visual Studio Code Version (x.x.x)
• Is this a local or cloud environment? (Cloud | Local)
• If Cloud, Browser (chrome, safari)
• If Local, OS (macOS, windows, linux)

Additional context
Add any other context about the problem here.