make protobuf optional

Signed-off-by: Gregor Zeitlinger <[email protected]>

Author: zeitlinger

integration-tests/it-exporter/it-no-protobuf/pom.xml

@@ -4,7 +4,7 @@
 
     <parent>
         <groupId>io.prometheus</groupId>
-        <artifactId>integration-tests</artifactId>
+        <artifactId>it-exporter</artifactId>
         <version>1.3.2</version>
     </parent>