This loosens our restrictions around processing package set updates. Previously, if you don't specify any packages then the update is not processed (there are no packages to update). However, this prevents us from updating the compiler version used to process package sets without also updating specific packages as seen in https://github.com/purescript/registry/issues/297.
With this PR we will process package set updates even if there are no packages if a) the compiler field is set and b) the specified compiler version is greater than the existing one.
This loosens our restrictions around processing package set updates. Previously, if you don't specify any packages then the update is not processed (there are no packages to update). However, this prevents us from updating the compiler version used to process package sets without also updating specific packages as seen in https://github.com/purescript/registry/issues/297.
With this PR we will process package set updates even if there are no packages if a) the compiler field is set and b) the specified compiler version is greater than the existing one.