Fix missing comma

Author: shakuzen

Diff for: micrometer-core/src/main/java/io/micrometer/core/instrument/binder/grpc/DefaultGrpcServerObservationConvention.java

@@ -44,7 +44,7 @@ public KeyValues getLowCardinalityKeyValues(GrpcServerObservationContext context
         String peerPort = context.getPeerPort() != null ? context.getPeerPort().toString() : UNKNOWN;
         return KeyValues.of(LowCardinalityKeyNames.STATUS_CODE.withValue(statusCode),
                 LowCardinalityKeyNames.PEER_NAME.withValue(peerName),
-                LowCardinalityKeyNames.PEER_PORT.withValue(peerPort)
+                LowCardinalityKeyNames.PEER_PORT.withValue(peerPort),
                 LowCardinalityKeyNames.METHOD.withValue(context.getMethodName()),
                 LowCardinalityKeyNames.SERVICE.withValue(context.getServiceName()),
                 LowCardinalityKeyNames.METHOD_TYPE.withValue(context.getMethodType().name()));