Ensure that only NuGet packages for the current version are pushed

We currently use this command to push the NuGet packages to nuget.org:

${nugetExe} push Gremlin.Net/bin/Gremlin.Net.*.nupkg [...]

which will push all versions of the package it can find in the Gremlin.Net/bin directory. The same applies to the Gremlin.Net.Template.

We should use the exact version here instead to avoid pushing packages for any other versions by accident.