Verify parent path is not-null

As a result of the new nullability annotations used in Gradle 9.0.0 an
explicit non-null check is now required here.

Author: erichaagdev

buildSrc/src/main/kotlin/ApplyArgbash.kt

@@ -42,10 +42,10 @@ abstract class ApplyArgbash @Inject constructor(
     fun applyArgbash() {
         val argbash = argbashHome.get().file("bin/argbash").asFile
         scriptTemplates.get().visit {
-            if(!isDirectory) {
-                val relPath = relativePath.parent.pathString
+            val relativePath = relativePath.parent?.pathString
+            if (!isDirectory && relativePath != null) {
                 val basename = file.nameWithoutExtension
-                val outputFile = outputDir.get().file("$relPath/$basename.sh").asFile
+                val outputFile = outputDir.get().file("$relativePath/$basename.sh").asFile
                 outputFile.parentFile.mkdirs()
 
                 logger.info("Applying argbash to $file")