fix uwp platformtarget for release build

Tests/MQTTnet.TestApp.UniversalWindows/MQTTnet.TestApp.UniversalWindows.csproj

@@ -166,7 +166,7 @@
     <NoWarn>;2008</NoWarn>
     <NoStdLib>true</NoStdLib>
     <DebugType>pdbonly</DebugType>
-    <PlatformTarget>AnyCPU</PlatformTarget>
+    <PlatformTarget>x86</PlatformTarget>
     <UseVSHostingProcess>false</UseVSHostingProcess>
     <ErrorReport>prompt</ErrorReport>
     <CodeAnalysisRuleSet>MinimumRecommendedRules.ruleset</CodeAnalysisRuleSet>