Bump js-yaml from 4.3.2 to 5.4.2 in /theme

Bumps [js-yaml](https://github.com/nodeca/js-yaml) from 4.3.2 to 5.4.2.
- [Changelog](https://github.com/nodeca/js-yaml/blob/master/CHANGELOG.md)
- [Commits](nodeca/js-yaml@4.3.2...5.4.2)

---
updated-dependencies:
- dependency-name: js-yaml
  dependency-version: 5.4.1
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

theme/package.json

@@ -58,7 +58,7 @@
   "dependencies": {
     "@fortawesome/fontawesome-free": "^7.0.1",
     "js-cookie": "^3.0",
-    "js-yaml": "^4.1",
+    "js-yaml": "^5.4",
     "tippy.js": "^6.3"
   }
 }

theme/yarn.lock

@@ -2375,13 +2375,20 @@ js-tokens@^4.0.0:
   resolved "https://registry.yarnpkg.com/js-tokens/-/js-tokens-4.0.0.tgz#19203fb59991df98e3a287050d4647cdeaf32499"
   integrity sha512-RdJUflcE3cUzKiMqQgsCu06FPu9UdIJO0beYbPhHN4k6apgJtifcoCtT9bcxOpYBtpD2kCM6Sbzg4CausW/PKQ==
 
-js-yaml@^4.1, js-yaml@^4.1.0:
+js-yaml@^4.1.0:
   version "4.3.2"
   resolved "https://registry.yarnpkg.com/js-yaml/-/js-yaml-4.3.2.tgz#8e44fb14a2643c59726bb15787b5f1512cb3d3fb"
   integrity sha512-SFNOvSJ+Dgf/9An904Yx+CgSlIPCkIpao4qo51lpee25TIRejdH3rhR4EZMGoNx3/TP3O+wzWuiTFl4sqbltzA==
   dependencies:
     argparse "^2.0.1"
 
+js-yaml@^5.4:
+  version "5.4.2"
+  resolved "https://registry.yarnpkg.com/js-yaml/-/js-yaml-5.4.2.tgz#eebc7a57e0bbe1d6b6d9416a72e7463082c7da85"
+  integrity sha512-m+aqu+LwO1O6sIopafj8HUVl5aawITwZQe/yHpMCKjaWBaA/d07B/QdMb3529REftiU+RMMHL3Vlsw3hON7vWg==
+  dependencies:
+    argparse "^2.0.1"
+
 jsesc@^3.0.2, jsesc@~3.1.0:
   version "3.1.0"
   resolved "https://registry.yarnpkg.com/jsesc/-/jsesc-3.1.0.tgz#74d335a234f67ed19907fdadfac7ccf9d409825d"