Bump handlebars from 4.1.2 to 4.5.3 in /packages/github (#276)

Bumps [handlebars](https://github.com/wycats/handlebars.js) from 4.1.2 to 4.5.3.
- [Release notes](https://github.com/wycats/handlebars.js/releases)
- [Changelog](https://github.com/wycats/handlebars.js/blob/master/release-notes.md)
- [Commits](https://github.com/wycats/handlebars.js/compare/v4.1.2...v4.5.3)

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

packages/github/package-lock.json

@@ -2365,9 +2365,9 @@
       "dev": true
     },
     "handlebars": {
-      "version": "4.1.2",
-      "resolved": "https://registry.npmjs.org/handlebars/-/handlebars-4.1.2.tgz",
-      "integrity": "sha512-nvfrjqvt9xQ8Z/w0ijewdD/vvWDTOweBUm96NTr66Wfvo1mJenBLwcYmPs3TIBP5ruzYGD7Hx/DaM9RmhroGPw==",
+      "version": "4.5.3",
+      "resolved": "https://registry.npmjs.org/handlebars/-/handlebars-4.5.3.tgz",
+      "integrity": "sha512-3yPecJoJHK/4c6aZhSvxOyG4vJKDshV36VHp0iVCDVh7o9w2vwi3NSnL2MMPj3YdduqaBcu7cGbggJQM0br9xA==",
       "dev": true,
       "requires": {
         "neo-async": "^2.6.0",