fix(build): fix artifact signing

Author: msfjarvis

build.gradle.kts

@@ -42,3 +42,9 @@ ktfmt {
   googleStyle()
   maxWidth.set(100)
 }
+
+signing {
+  val signingKey: String? by project
+  val signingPassword: String? by project
+  useInMemoryPgpKeys(signingKey, signingPassword)
+}