feat(deps): bump github.com/xhit/go-simple-mail/v2 from 2.15.0 to 2.16.0 (#30)

Bumps [github.com/xhit/go-simple-mail/v2](https://github.com/xhit/go-simple-mail) from 2.15.0 to 2.16.0.
- [Release notes](https://github.com/xhit/go-simple-mail/releases)
- [Commits](https://github.com/xhit/go-simple-mail/compare/v2.15.0...v2.16.0)

---
updated-dependencies:
- dependency-name: github.com/xhit/go-simple-mail/v2
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

go.mod

@@ -11,7 +11,7 @@ require (
 	github.com/muesli/roff v0.1.0
 	github.com/resendlabs/resend-go v1.7.0
 	github.com/spf13/cobra v1.7.0
-	github.com/xhit/go-simple-mail/v2 v2.15.0
+	github.com/xhit/go-simple-mail/v2 v2.16.0
 	github.com/yuin/goldmark v1.5.6
 )