Serilog dependency version fix.

Author: nblumhardt

src/Serilog.Sinks.AzureTableStorage/Serilog.Sinks.AzureTableStorage.nuspec

@@ -11,7 +11,7 @@
     <iconUrl>http://serilog.net/images/serilog-sink-nuget.png</iconUrl>
     <tags>serilog logging azure</tags>
     <dependencies>
-      <dependency id="Serilog" version="$version$" />
+      <dependency id="Serilog" version="1.4" />
       <dependency id="WindowsAzure.Storage" version="2.0" />
     </dependencies>
   </metadata>