Bump govspeak from 8.5.1 to 8.6.0

Bumps [govspeak](https://github.com/alphagov/govspeak) from 8.5.1 to 8.6.0.
- [Changelog](https://github.com/alphagov/govspeak/blob/main/CHANGELOG.md)
- [Commits](alphagov/govspeak@v8.5.1...v8.6.0)

---
updated-dependencies:
- dependency-name: govspeak
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Gemfile.lock

@@ -109,7 +109,7 @@ GEM
       rack-test (>= 0.6.3)
       regexp_parser (>= 1.5, < 3.0)
       xpath (~> 3.2)
-    chartkick (5.1.1)
+    chartkick (5.1.2)
     chronic (0.10.2)
     climate_control (1.2.0)
     coderay (1.1.3)
@@ -183,7 +183,7 @@ GEM
       rake (>= 13)
     googleapis-common-protos-types (1.16.0)
       google-protobuf (>= 3.18, < 5.a)
-    govspeak (8.5.1)
+    govspeak (8.6.0)
       actionview (>= 6, < 7.2.2)
       addressable (>= 2.3.8, < 2.8.8)
       govuk_publishing_components (>= 35.1)