Update dependency com.squareup.okio:okio to v3.15.0 (#415)

Author: renovate[bot]

gradle/libs.versions.toml

@@ -5,7 +5,7 @@ openapi-generator = "7.12.0"
 jupyter-api = "0.12.0-398"
 jupyter-testkit = "0.12.0-398"
 jupyter-plugin = "0.12.0-398"
-okio = "3.11.0"
+okio = "3.15.0"
 moshi = "1.15.2"
 okhttp = "4.12.0"
 retrofit = "2.11.0"