Deps: Group kotlin & ksp dependabot updates

With this configuration Dependabot should update both, the 'Kotlin' and
'KSP' related dependencies in one go, on a single Dependabot related PR.

FYI: Using the 'applies-to key' is optional. If the 'applies-to key' is
absent from a set of grouping rules, it defaults to 'version-updates'
for backwards compatibility. I chose to use 'applies-to' in order to be
explicit about this and avoid any confusion related to the defaults.

For more info see: https://docs.github.com/en/code-security/
dependabot/dependabot-version-updates/
configuration-options-for-the-dependabot.yml-file#groups

.github/dependabot.yml

@@ -9,6 +9,14 @@ updates:
       - "bot: dependencies update"
     reviewers:
       - "wordpress-mobile/android-developers"
+    groups:
+      kotlin-ksp:
+        applies-to: version-updates
+        patterns:
+          - "org.jetbrains.kotlin*"
+          - "com.google.devtools.ksp*"
+        exclude-patterns:
+          - "org.jetbrains.kotlinx*"
     ignore:
       # The Android Gradle Plugin is a dependency that needs to be in sync with other
       # in-house libraries due to compatibility with composite build.