fix(deps): update spring boot to v3.5.15 (#40)

Co-authored-by: Renovate Bot <renovate@whitesourcesoftware.com>

Author: rossdanderson

gradle/libs.versions.toml

@@ -1,5 +1,5 @@
 [versions]
-springBoot = "3.5.14"
+springBoot = "3.5.15"
 kotlin = "2.2.0"
 kotlinCollectionsImmutable = "0.5.0"
 jackson3 = "3.1.3"