workaround ContainerApps bug in volume mounts

[et1975]

This PR fixes current master and works around ContainerApps bug that can't handle empty volumes/mounts on redeployment.

I have read the contributing guidelines and have completed the following:

• [x] Tested my code end-to-end against a live Azure subscription.
• [ ] Updated the documentation in the docs folder for the affected changes.
• [ ] Written unit tests against the modified code that I have made.
• [x] Updated the release notes with a new entry for this PR.
• [x] Checked the coding standards outlined in the contributions guide and ensured my code adheres to them.

If I haven't completed any of the tasks above, I include the reasons why here: seemed reasonable

[ninjarobot]

Thanks for the fix, this is now released in 1.7.5 and available on nuget.