fix(deps): update dependency io.micronaut:micronaut-core-bom to v4.8.4 (#483)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

gradle/libs.versions.toml

@@ -1,5 +1,5 @@
 [versions]
-micronaut = "4.8.3"
+micronaut = "4.8.4"
 micronaut-docs = "2.0.0"
 managed-hibernate-validator = '8.0.2.Final'