Upgrade to Prometheus Client 0.16.0

Closes gh-31597

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/export/prometheus/PrometheusMetricsExportAutoConfigurationTests.java

@@ -305,6 +305,11 @@ class PrometheusMetricsExportAutoConfigurationTests {
 					return null;
 				}
 
+				@Override
+				public boolean isSampled() {
+					return false;
+				}
+
 			};
 		}
 

spring-boot-project/spring-boot-dependencies/build.gradle

@@ -1126,7 +1126,7 @@ bom {
 			]
 		}
 	}
-	library("Prometheus Client", "0.15.0") {
+	library("Prometheus Client", "0.16.0") {
 		group("io.prometheus") {
 			imports = [
 				"simpleclient_bom"