Bump github.com/apple/swift-docc-plugin from 1.3.0 to 1.4.2

Bumps [github.com/apple/swift-docc-plugin](https://github.com/apple/swift-docc-plugin) from 1.3.0 to 1.4.2.
- [Release notes](https://github.com/apple/swift-docc-plugin/releases)
- [Commits](swiftlang/swift-docc-plugin@1.3.0...1.4.2)

---
updated-dependencies:
- dependency-name: github.com/apple/swift-docc-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Package.resolved

@@ -5,14 +5,14 @@
  "kind" : "remoteSourceControl",
  "location" : "https://github.com/apple/swift-docc-plugin",
  "state" : {
- "revision" : "26ac5758409154cc448d7ab82389c520fa8a8247",
- "version" : "1.3.0"
+ "revision" : "2eb22993b3dfd0c0d32729b357c8dabb6cd44680",
+ "version" : "1.4.2"
  }
  },
  {
  "identity" : "swift-docc-symbolkit",
  "kind" : "remoteSourceControl",
- "location" : "https://github.com/apple/swift-docc-symbolkit",
+ "location" : "https://github.com/swiftlang/swift-docc-symbolkit",
  "state" : {
  "revision" : "b45d1f2ed151d057b54504d653e0da5552844e34",
  "version" : "1.0.0"