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] <support@github.com>

Package.resolved

@@ -32,14 +32,14 @@
       "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"