build(deps): Bump @x-govuk/govuk-eleventy-plugin from 7.2.1 to 8.3.0 in the production-dependencies group (#25)

* build(deps): Bump @x-govuk/govuk-eleventy-plugin

Bumps the production-dependencies group with 1 update: [@x-govuk/govuk-eleventy-plugin](https://github.com/x-govuk/govuk-eleventy-plugin).


Updates `@x-govuk/govuk-eleventy-plugin` from 7.2.1 to 8.3.0
- [Release notes](https://github.com/x-govuk/govuk-eleventy-plugin/releases)
- [Commits](x-govuk/govuk-eleventy-plugin@v7.2.1...v8.3.0)

---
updated-dependencies:
- dependency-name: "@x-govuk/govuk-eleventy-plugin"
  dependency-version: 8.3.0
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: production-dependencies
...

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

* fix: remove custom 404.md to use plugin default

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Chris Nesbitt-Smith <chris@cns.me.uk>

Author: dependabot[bot]

package-lock.json

@@ -32,7 +32,7 @@
   "license": "MIT",
   "dependencies": {
     "@sindresorhus/slugify": "^3.0.0",
-    "@x-govuk/govuk-eleventy-plugin": "^7.0.0",
+    "@x-govuk/govuk-eleventy-plugin": "^8.3.0",
     "govuk-frontend": "5.13.0",
     "jspdf": "^4.0.0",
     "markdown-it": "^14.1.0"