Bump handlebars from 4.7.6 to 4.7.7 in /frontend

Bumps [handlebars](https://github.com/wycats/handlebars.js) from 4.7.6 to 4.7.7.
- [Release notes](https://github.com/wycats/handlebars.js/releases)
- [Changelog](https://github.com/handlebars-lang/handlebars.js/blob/master/release-notes.md)
- [Commits](handlebars-lang/handlebars.js@v4.7.6...v4.7.7)

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

frontend/yarn.lock

@@ -4622,9 +4622,9 @@ handle-thing@^2.0.0:
   integrity sha512-d4sze1JNC454Wdo2fkuyzCr6aHcbL6PGGuFAz0Li/NcOm1tCHGnWDRmJP85dh9IhQErTc2svWFEX5xHIOo//kQ==
 
 handlebars@^4.1.2:
-  version "4.7.6"
-  resolved "https://registry.yarnpkg.com/handlebars/-/handlebars-4.7.6.tgz#d4c05c1baf90e9945f77aa68a7a219aa4a7df74e"
-  integrity sha512-1f2BACcBfiwAfStCKZNrUCgqNZkGsAT7UM3kkYtXuLo0KnaVfjKOyf7PRzB6++aK9STyT1Pd2ZCPe3EGOXleXA==
+  version "4.7.7"
+  resolved "https://registry.yarnpkg.com/handlebars/-/handlebars-4.7.7.tgz#9ce33416aad02dbd6c8fafa8240d5d98004945a1"
+  integrity sha512-aAcXm5OAfE/8IXkcZvCepKU3VzW1/39Fb5ZuqMtgI/hT8X2YgoMvBY5dLhq/cpOvw7Lk1nK/UF71aLG/ZnVYRA==
   dependencies:
     minimist "^1.2.5"
     neo-async "^2.6.0"
@@ -9959,9 +9959,9 @@ uglify-js@3.4.x:
     source-map "~0.6.1"
 
 uglify-js@^3.1.4:
-  version "3.10.4"
-  resolved "https://registry.yarnpkg.com/uglify-js/-/uglify-js-3.10.4.tgz#dd680f5687bc0d7a93b14a3482d16db6eba2bfbb"
-  integrity sha512-kBFT3U4Dcj4/pJ52vfjCSfyLyvG9VYYuGYPmrPvAxRw/i7xHiT4VvCev+uiEMcEEiu6UNB6KgWmGtSUYIWScbw==
+  version "3.13.5"
+  resolved "https://registry.yarnpkg.com/uglify-js/-/uglify-js-3.13.5.tgz#5d71d6dbba64cf441f32929b1efce7365bb4f113"
+  integrity sha512-xtB8yEqIkn7zmOyS2zUNBsYCBRhDkvlNxMMY2smuJ/qA8NCHeQvKCF3i9Z4k8FJH4+PJvZRtMrPynfZ75+CSZw==
 
 unicode-canonical-property-names-ecmascript@^1.0.4:
   version "1.0.4"