Fix chef apt source

[timothegenzmer]

Proposed Commit Message

Fix chef apt source

summary: Fix chef apt source

key is a property of source1 and not sources

Additional Context

Test Steps

try to add a apt repository with the old docs
apt repository wont be added

Checklist:

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly
• I have updated or added any documentation accordingly

[TheRealFalcon]

Thanks for this change! Before we can get this merged, you need to add your name to the CLA signers file. As part of this PR, please add your name (alphabetically) to https://github.com/canonical/cloud-init/blob/master/tools/.github-cla-signers . The full details are described in the last bullet point here: https://cloudinit.readthedocs.io/en/latest/topics/hacking.html#submitting-your-first-pull-request

[TheRealFalcon]

Nit: this line shouldn't have the additional whitespace.

[github-actions]

Hello! Thank you for this proposed change to cloud-init. This pull request is now marked as stale as it has not seen any activity in 14 days. If no activity occurs within the next 7 days, this pull request will automatically close.

If you are waiting for code review and you are seeing this message, apologies! Please reply, tagging mitechie, and he will ensure that someone takes a look soon.

(If the pull request is closed and you would like to continue working on it, please do tag mitechie to reopen it.)