Update dependency org.jellyfin.sdk:jellyfin-core to v1.6.8

Author: renovate[bot]

Diff for: gradle/libs.versions.toml

@@ -27,7 +27,7 @@ coil = "3.1.0"
 detekt = "1.23.8"
 java-jdk = "21"
 jellyfin-androidx-media = "1.5.0+1"
-jellyfin-sdk = "1.6.7"
+jellyfin-sdk = "1.6.8"
 koin = "4.0.4"
 koin-compose = "4.0.4"
 kotest = "5.9.1"