feature: extend tauri builder with updater_header method

What kind of change does this PR introduce?

• [ ] Bugfix
• [x] Feature
• [ ] Docs
• [ ] New Binding issue #___
• [ ] Code style update
• [ ] Refactor
• [ ] Build-related changes
• [ ] Other, please describe:

Does this PR introduce a breaking change?

• [ ] Yes, and the changes were approved in issue #___
• [x] No

Checklist

• [x] When resolving issues, they are referenced in the PR's title (e.g fix: remove a typo, closes #___, #___)
• [x] A change file is added if any packages will require a version bump due to this PR per the instructions in the readme.
• [x] I have added a convincing reason for adding this feature, if necessary

Other information

This change extends tauri::Builder with a new method updater_header (in the same vein as the existing updater_target) to set headers on the default updater instance.