plugin: enable deterministic builds in CI

Author: JohnTheGr8

Flow.Launcher.Plugin/Flow.Launcher.Plugin.csproj

@@ -28,6 +28,10 @@
     <PublishRepositoryUrl>true</PublishRepositoryUrl>
   </PropertyGroup>
 
+  <PropertyGroup Condition="'$(APPVEYOR)' == 'True'">
+    <ContinuousIntegrationBuild>true</ContinuousIntegrationBuild>
+  </PropertyGroup>
+
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DebugSymbols>true</DebugSymbols>
     <DebugType>full</DebugType>