Fix a test failure by force flushing, fixes #156

Author: duncanpo

test/tmetrics_sdk.m

@@ -95,6 +95,7 @@ function testOtlpFileExporter(testCase)
             ct.add(val);
 
             % fetch result
+            forceFlush(p);
             clear("ct", "mt", "p");
             results = jsondecode(fileread(alias));
 
@@ -539,4 +540,4 @@ function testCleanupApi(testCase)
             verifyEmpty(testCase, results);
         end
     end
-end
+end