Bump the copyright year

Author: jcansdale

src/common/SolutionInfo.cs

@@ -5,7 +5,7 @@
 [assembly: AssemblyProduct("GitHub Extension for Visual Studio")]
 [assembly: ComVisible(false)]
 [assembly: AssemblyCompany("GitHub, Inc.")]
-[assembly: AssemblyCopyright("Copyright © GitHub, Inc. 2014-2016")]
+[assembly: AssemblyCopyright("Copyright © GitHub, Inc. 2014-2019")]
 [assembly: AssemblyConfiguration("")]
 [assembly: AssemblyTrademark("")]
 [assembly: AssemblyCulture("")]