Build(deps): Bump deepmerge in /app/assets/javascripts (#20732)

Bumps [deepmerge](https://github.com/TehShrike/deepmerge) from 4.3.0 to 4.3.1.
- [Release notes](https://github.com/TehShrike/deepmerge/releases)
- [Changelog](https://github.com/TehShrike/deepmerge/blob/master/changelog.md)
- [Commits](https://github.com/TehShrike/deepmerge/compare/v4.3.0...v4.3.1)

---
updated-dependencies:
- dependency-name: deepmerge
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

app/assets/javascripts/discourse/package.json

@@ -44,7 +44,7 @@
     "bootstrap": "3.4.1",
     "bootstrap-json": "1.0.0",
     "broccoli-asset-rev": "^3.0.0",
-    "deepmerge": "^4.3.0",
+    "deepmerge": "^4.3.1",
     "dialog-holder": "1.0.0",
     "discourse-common": "1.0.0",
     "discourse-hbr": "1.0.0",

app/assets/javascripts/yarn.lock

@@ -3573,10 +3573,10 @@ deep-is@^0.1.3, deep-is@~0.1.3:
   resolved "https://registry.yarnpkg.com/deep-is/-/deep-is-0.1.3.tgz#b369d6fb5dbc13eecf524f91b070feedc357cf34"
   integrity sha1-s2nW+128E+7PUk+RsHD+7cNXzzQ=
 
-deepmerge@^4.3.0:
-  version "4.3.0"
-  resolved "https://registry.yarnpkg.com/deepmerge/-/deepmerge-4.3.0.tgz#65491893ec47756d44719ae520e0e2609233b59b"
-  integrity sha512-z2wJZXrmeHdvYJp/Ux55wIjqo81G5Bp4c+oELTW+7ar6SogWHajt5a9gO3s3IDaGSAXjDk0vlQKN3rms8ab3og==
+deepmerge@^4.3.1:
+  version "4.3.1"
+  resolved "https://registry.yarnpkg.com/deepmerge/-/deepmerge-4.3.1.tgz#44b5f2147cd3b00d4b56137685966f26fd25dd4a"
+  integrity sha512-3sUqbMEc77XqpdNO7FRyRog+eW3ph+GYCbj+rK+uYyRMuwsVy0rMiVtPn+QJlKFvWP/1PYpapqYn0Me2knFn+A==
 
 defaults@^1.0.3:
   version "1.0.3"