Update gradle-oci to 0.21.0

Author: SgtSilvio

build.gradle.kts

@@ -49,14 +49,12 @@ oci {
             dependencies {
                 runtime("com.hivemq:hivemq-enterprise:latest") { isChanging = true }
             }
-            layers {
-                layer("main") {
-                    contents {
-                        permissions("opt/hivemq/", 0b111_111_101)
-                        permissions("opt/hivemq/extensions/", 0b111_111_101)
-                        into("opt/hivemq/extensions") {
-                            from(zipTree(tasks.hivemqExtensionZip.flatMap { it.archiveFile }))
-                        }
+            layer("main") {
+                contents {
+                    permissions("opt/hivemq/", 0b111_111_101)
+                    permissions("opt/hivemq/extensions/", 0b111_111_101)
+                    into("opt/hivemq/extensions") {
+                        from(zipTree(tasks.hivemqExtensionZip.flatMap { it.archiveFile }))
                     }
                 }
             }

gradle/libs.versions.toml

@@ -26,4 +26,4 @@ testcontainers-toxiproxy = { module = "org.testcontainers:toxiproxy", version.re
 defaults = { id = "io.github.sgtsilvio.gradle.defaults", version = "0.2.0" }
 hivemq-extension = { id = "com.hivemq.extension", version = "3.2.0" }
 license = { id = "com.github.hierynomus.license", version = "0.16.1" }
-oci = { id = "io.github.sgtsilvio.gradle.oci", version = "0.20.2" }
+oci = { id = "io.github.sgtsilvio.gradle.oci", version = "0.21.0" }