Bump slimmer from 16.0.1 to 17.0.0

Bumps [slimmer](https://github.com/alphagov/slimmer) from 16.0.1 to 17.0.0.
- [Release notes](https://github.com/alphagov/slimmer/releases)
- [Changelog](https://github.com/alphagov/slimmer/blob/master/CHANGELOG.md)
- [Commits](alphagov/slimmer@v16.0.1...v17.0.0)

---
updated-dependencies:
- dependency-name: slimmer
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

Gemfile.lock

@@ -150,7 +150,7 @@ GEM
     http-accept (1.7.0)
     http-cookie (1.0.4)
       domain_name (~> 0.5)
-    i18n (1.9.1)
+    i18n (1.10.0)
       concurrent-ruby (~> 1.0)
     i18n-coverage (0.2.0)
     i18n-tasks (0.9.37)
@@ -333,7 +333,7 @@ GEM
       docile (~> 1.1)
       simplecov-html (~> 0.11)
     simplecov-html (0.12.3)
-    slimmer (16.0.1)
+    slimmer (17.0.0)
       activesupport
       json
       nokogiri (~> 1.7)