fix(deps): update dependency io.micrometer:micrometer-registry-prometheus to v1.15.4

Author: renovate[bot]

spring-prometheus-grafana-example/pom.xml

@@ -20,7 +20,7 @@
 	<properties>
 		<java.version>21</java.version>
 		<spring.boot.version>3.5.5</spring.boot.version>
-		<io.micrometer.version>1.15.3</io.micrometer.version>
+		<io.micrometer.version>1.15.4</io.micrometer.version>
 	</properties>
 
 	<dependencies>