Use relative path sensitivity in the license gather plugin

This adds relative path sensitivity for configurations and extra
licenses. This will avoid build caching issues with the extra licenses
 directory because cache keys will no longer depend on absolute paths.

Author: Sandra Thieme

plugins/license-gather-plugin/src/main/kotlin/com/github/vlsi/gradle/license/GatherLicenseTask.kt

@@ -42,6 +42,8 @@ import org.gradle.api.tasks.InputFiles
 import org.gradle.api.tasks.Internal
 import org.gradle.api.tasks.Optional
 import org.gradle.api.tasks.OutputDirectory
+import org.gradle.api.tasks.PathSensitive
+import org.gradle.api.tasks.PathSensitivity
 import org.gradle.api.tasks.TaskAction
 import org.gradle.internal.component.external.model.DefaultModuleComponentIdentifier
 import org.gradle.kotlin.dsl.dependencies
@@ -106,6 +108,7 @@ open class GatherLicenseTask @Inject constructor(
     }
 
     @InputFiles
+    @PathSensitive(PathSensitivity.RELATIVE)
     val configurations = objectFactory.setProperty<Configuration>()
 
     @Input
@@ -172,6 +175,7 @@ open class GatherLicenseTask @Inject constructor(
 
     @InputFiles
     @Optional
+    @PathSensitive(PathSensitivity.RELATIVE)
     val extraLicenseDir = objectFactory.directoryProperty().convention(
         project.layout.projectDirectory.dir("licenses")
     )