chore(deps): Bump handlebars in /build/frontend-legacy

Bumps [handlebars](https://github.com/handlebars-lang/handlebars.js) from 4.7.8 to 4.7.9.
- [Release notes](https://github.com/handlebars-lang/handlebars.js/releases)
- [Changelog](https://github.com/handlebars-lang/handlebars.js/blob/v4.7.9/release-notes.md)
- [Commits](handlebars-lang/handlebars.js@v4.7.8...v4.7.9)

---
updated-dependencies:
- dependency-name: handlebars
  dependency-version: 4.7.9
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

build/frontend-legacy/package-lock.json

@@ -67,7 +67,7 @@
     "dompurify": "^3.4.0",
     "escape-html": "^1.0.3",
     "focus-trap": "^8.0.1",
-    "handlebars": "^4.7.8",
+    "handlebars": "^4.7.9",
     "is-svg": "^6.1.0",
     "libphonenumber-js": "^1.12.40",
     "lodash": "^4.18.1",