fix import

Author: Siedlerchr

jabsrv/src/main/java/org/jabref/http/server/command/CommandResource.java

@@ -9,6 +9,7 @@
 import jakarta.ws.rs.core.Response;
 import org.glassfish.hk2.api.ServiceLocator;
 import tools.jackson.core.JacksonException;
+import tools.jackson.databind.ObjectMapper;
 import tools.jackson.databind.json.JsonMapper;
 
 @Path("commands")