BREAKING CHANGE(web-twig): Remove deprecated Header component #652

 ## Migration Guide

The deprecated `Header` JS plugin was removed in favour of the
`Offcanvas` plugin.

- `import { Header } from '@lmc-eu/spirit-web'` → `import { Offcanvas } from '@lmc-eu/spirit-web'`
- `data-toggle="header"` → `data-spirit-toggle="offcanvas"`
(`spirit` infix is made mandatory in PR #935)
- `data-dismiss="header"` → `data-spirit-dismiss="offcanvas"`
(`spirit` infix is made mandatory in PR #935)

Please refer back to these instructions or reach out to our team
if you encounter any issues during migration.

packages/web-twig/src/Resources/components/Header/README.md

@@ -38,11 +38,6 @@ plugins.
 
 Or, feel free to write the controlling script yourself.
 
-### DEPRECATION NOTICE
-
-⚠️ The existing Header JavaScript plugin is deprecated and will be superseded
-by the Off-canvas plugin in the next major version.
-
 ## Accessibility Guidelines
 
 👉 The animation effect of this component is dependent on the