fix(deps): update dependency io.micronaut:micronaut-core-bom to v4.8.4

Author: renovate[bot]

gradle/libs.versions.toml

@@ -1,6 +1,6 @@
 [versions]
 micronaut-docs = "2.0.0"
-micronaut = "4.7.13"
+micronaut = "4.8.4"
 micronaut-platform = "4.5.1"
 micronaut-security = "4.11.3"
 micronaut-logging = "1.4.0"