extension_ci: Specify needed permissions for jobs (#45542)

GitHub flags these as security vulnerabilities. Hence, this PR specifies
the needed permissions for the workflows used in the `zed-extensions`
organization.

Release Notes:

- N/A
1d006a8cb0Finn Evers committed on 12/29/2025, 1:19:22 PM· committed by GitHubparentaaab9f6
10 files changedLine totals unavailable