Update ESLint version in "Check JavaScript" template installation docs

ESLint 8.21.0 is now the version used as standard in all Arduino Tooling projects.

Author: per1234

workflow-templates/check-javascript-task.md

@@ -31,7 +31,7 @@ The tool dependencies of this workflow are managed by [npm](https://www.npmjs.co
 Add the dependencies by running this command:
 
 ```text
-npm install --save-dev eslint@^8.20.0 eslint-config-prettier@^8.5.0
+npm install --save-dev eslint@^8.21.0 eslint-config-prettier@^8.5.0
 npx install-peerdeps --dev eslint-config-airbnb-base
 ```