Update prometheus-net to latest patch version

OhmGraphite/OhmGraphite.csproj

@@ -30,7 +30,7 @@
     <PackageReference Include="ILRepack" Version="2.0.16" />
     <PackageReference Include="NLog.Config" Version="4.5.10" />
     <PackageReference Include="Npgsql" Version="4.0.3" />
-    <PackageReference Include="prometheus-net" Version="2.1.2" />
+    <PackageReference Include="prometheus-net" Version="2.1.3" />
     <PackageReference Include="TopShelf" Version="4.1.0" />
     <PackageReference Include="Topshelf.NLog" Version="4.1.0" />
     <PackageReference Include="InfluxDB.LineProtocol" Version="1.1.0" />