wix installer is also signed

[Niedzwiedzw]

What kind of change does this PR introduce?

Signing a binary that goes into wix is great, but end user will still experience a malware warning unless the wix installer itself is also signed.

• Bugfix
• 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 #___
• No

Checklist

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

Other information

[lucasfernog]

Can you add a .md file on the .changes folder describing this change, so it can be added to the changelog? Like this:

.changes/wix-signing.md

---
"tauri-bundler": patch
---

Sign WiX installer in addition to the executable file.

[ImmaZoni]

I was trying to fix this, glad you beat me to the punch!

Thanks a bunch!