Fix lowest_matching constraint out of sync

[klettier]

Lowest_matching constraint isn't working when you set it at group level.

Cause : The lowest_matching constraint isn't wrote into paket.lock file when the paket install occurs

You can reproduce the out of sync error with this simple paket.dependencies content

source https://www.nuget.org/api/v2

lowest_matching: true

In paket verion 2.66.9.0 the command succeed but does not populate the paket.lock file

--------------------------------In paket version 2.66.9.0--------------------------------
$ paket install
Paket version 2.66.9.0
Resolving packages for group Main:
Locked version resolution written to ...\paket.lock
0 seconds - ready.

$ paket restore
Paket version 2.66.9.0
0 seconds - ready.

In current paket version the command failed

--------------------------------In paket version 3.16.0.0--------------------------------

$ .paket/paket install
Paket version 3.16.0.0
Resolving packages for group Main:
...\paket.lock is already up-to-date
0 seconds - ready.


$ .paket/paket restore
Paket version 3.16.0.0
paket.dependencies and paket.lock are out of sync in ...
Please run 'paket install' or 'paket update' to recompute the paket.lock file.
0 seconds - ready.

[forki]

cool thanks!