only set file timestamps and permissions for jar

* this does not touch the other artifacts like source distribution and thus avoids problems with files like gradlew not being executable
diff --git a/build.gradle.kts b/build.gradle.kts
index 34461d7..dd1bf0b 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -38,13 +38,17 @@
 }
 
 tasks.withType<AbstractArchiveTask>().configureEach {
-  isPreserveFileTimestamps = false
-  isReproducibleFileOrder = true
-  filePermissions {
-    unix("rw-r--r--")
-  }
-  dirPermissions {
-    unix("rwxr-xr-x")
+
+  if (name == "jar") {  
+    // make contents of freemarker.jar reproducible
+    isPreserveFileTimestamps = false
+    isReproducibleFileOrder = true
+    filePermissions {
+        unix("rw-r--r--")
+    }
+    dirPermissions {
+        unix("rwxr-xr-x")
+    }
   }
 }