Bump echarts-api from 4.6.0-7 to 4.6.0-8

Bumps [echarts-api](https://github.com/jenkinsci/echarts-api-plugin) from 4.6.0-7 to 4.6.0-8.
- [Release notes](https://github.com/jenkinsci/echarts-api-plugin/releases)
- [Changelog](https://github.com/jenkinsci/echarts-api-plugin/blob/master/CHANGELOG.md)
- [Commits](jenkinsci/echarts-api-plugin@echarts-api-4.6.0-7...echarts-api-4.6.0-8)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Author: dependabot-preview[bot]

pom.xml

@@ -37,7 +37,7 @@
     <jquery3-api.version>3.4.1-10</jquery3-api.version>
     <bootstrap4-api.version>4.4.1-10</bootstrap4-api.version>
     <data-tables-api.version>1.10.20-13</data-tables-api.version>
-    <echarts-api.version>4.6.0-7</echarts-api.version>
+    <echarts-api.version>4.6.0-8</echarts-api.version>
     <plugin-util-api.version>1.0.2</plugin-util-api.version>
 
   </properties>