Bump highcharts from 12.5.0 to 12.6.0 in /Plan/react/dashboard

Bumps [highcharts](https://github.com/highcharts/highcharts-dist) from 12.5.0 to 12.6.0.
- [Commits](highcharts/highcharts-dist@v12.5.0...v12.6.0)

---
updated-dependencies:
- dependency-name: highcharts
  dependency-version: 12.6.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

Plan/react/dashboard/package.json

@@ -25,7 +25,7 @@
     "bootstrap": "5.3.8",
     "date-fns-tz": "3.2.0",
     "export-to-csv": "1.4.0",
-    "highcharts": "12.5.0",
+    "highcharts": "12.6.0",
     "i18next": "26.0.8",
     "i18next-chained-backend": "5.0.3",
     "i18next-http-backend": "4.0.0",

Plan/react/dashboard/yarn.lock

@@ -1073,10 +1073,10 @@ hasown@^2.0.2:
   dependencies:
     function-bind "^1.1.2"
 
-highcharts@12.5.0:
-  version "12.5.0"
-  resolved "https://registry.yarnpkg.com/highcharts/-/highcharts-12.5.0.tgz#1cf5bc1214bb7bbd717096420089d130e84847ff"
-  integrity sha512-uNSSv1KqRLNvkyXlf1FbeGWB1mJ/8/IYpVeqYiTIop5Wo8peUvNyzUfLa58vILsmXyz+XrETtgKIEOcSgBBKuQ==
+highcharts@12.6.0:
+  version "12.6.0"
+  resolved "https://registry.yarnpkg.com/highcharts/-/highcharts-12.6.0.tgz#5e527c3cc41b858edf8d72f129808a167604a939"
+  integrity sha512-zWwoXECOakJT2huBMqIZOjDNLLgyZFCcfZqTj2g6cvYOGxjF3nvooC+rIaF5aKiharluyGKNflfRNrzOAIjdRg==
 
 hoist-non-react-statics@^3.3.1:
   version "3.3.2"