chore(BuildTools): Update version to enable updates

[corkupine]

This should enable updates. If there is something undesirable about this, let me know and feel free to close.

[jberezanski]

This, by itself, will have no effect.

Upgrading Visual Studio 2017 is something I have been working on for a long time (#10, this branch) and it is no easy task. I mean, passing the "update" command instead of "install" to the VS installer is trivial, but the hard task is to avoid the many pitfalls, quirks, unexpected behavior and bugs in the VS Installer (#7, #8, #13, #26, #29, #30 and that's not the complete list). That is why the officially released packages are explicitly not doing anything if they detect that Visual Studio is already installed.

Therefore, this pull request would only result in users getting this warning:

WARNING: Visual Studio 2017 Build Tools is already installed. Please use the Visual Studio Installer to modify or repair it.

and, if they did not read it but only looked at the output of clist -lo, they would see the increased package version and mistakenly believe that the Build Tools got updated.

The good news is that I'm nearing completion of the update mechanism. The current working prototype of is available for testing here: visualstudio2017buildtools, visualstudio2017-workload-webbuildtools, visualstudio2017-workload-netcorebuildtools. Once it is complete, I intend to set up an automated mechanism to update the packages (bump versions) whenever a new VS version is released.

So in the light of the above I'm closing this PR. Thank you, however, for motivating me to resume working :)

[corkupine]

Thank you for the detailed explanation!