Update plugin buildconfig to v5.7.1

Author: renovate[bot]

gradle/libs.versions.toml

@@ -51,4 +51,4 @@ kotlinx-serialization = { id = "org.jetbrains.kotlin.plugin.serialization", vers
 pluginPublish = { id = "com.gradle.plugin-publish", version.ref = "pluginPublish" }
 ktor = { id = "io.ktor.plugin", version.ref = "ktor-plugin" } # The published plugin
 binaryCompatibilityValidator = { id = "org.jetbrains.kotlinx.binary-compatibility-validator", version.ref = "binaryCompatibilityValidator" }
-buildconfig = { id = "com.github.gmazzo.buildconfig", version = "5.6.8" }
+buildconfig = { id = "com.github.gmazzo.buildconfig", version = "5.7.1" }