update an import for a dependency change

Author: jkwatson

exporters/prometheus/src/test/java/io/opentelemetry/exporter/prometheus/PrometheusHttpServerTest.java

@@ -46,7 +46,7 @@
 import io.opentelemetry.sdk.resources.Resource;
 import io.prometheus.metrics.exporter.httpserver.HTTPServer;
 import io.prometheus.metrics.exporter.httpserver.MetricsHandler;
-import io.prometheus.metrics.expositionformats.generated.com_google_protobuf_4_31_0.Metrics;
+import io.prometheus.metrics.expositionformats.generated.com_google_protobuf_4_31_1.Metrics;
 import io.prometheus.metrics.model.registry.PrometheusRegistry;
 import java.io.ByteArrayInputStream;
 import java.io.IOException;