bump NLog dependency in Program plugin

from 4.7.0-rc1 to 4.7.0

Author: JohnTheGr8

Plugins/Flow.Launcher.Plugin.Program/Flow.Launcher.Plugin.Program.csproj

@@ -110,7 +110,7 @@
     <PackageReference Include="JetBrains.Annotations" Version="2019.1.3" />
     <PackageReference Include="Microsoft.Windows.SDK.Contracts" Version="10.0.18362.2005" />
     <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
-    <PackageReference Include="NLog" Version="4.7.0-rc1" />
+    <PackageReference Include="NLog" Version="4.7.0" />
     <PackageReference Include="System.Runtime" Version="4.3.1" />
   </ItemGroup>