fix(deps): update dependency io.micronaut:micronaut-core-bom to v4.8.12 (#512)

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

Author: renovate[bot]

gradle/libs.versions.toml

@@ -1,6 +1,6 @@
 [versions]
 micronaut-docs = "2.0.0"
-micronaut = "4.8.11"
+micronaut = "4.8.12"
 micronaut-gradle-plugin = "4.4.5"
 groovy = "4.0.24"
 spock = "2.3-groovy-4.0"