fix: correct namespace imports for golem 0.4.0

[ColinFay]

The upcoming version of {golem} will have functions that override the {pkgload} functions.

This creates a namespace conflict with your package :

> devtools::document()
ℹ Updating MainExistingDatasets documentation
Setting `RoxygenNote` to "7.2.3"
ℹ Loading MainExistingDatasets
Writing NAMESPACE
Warning messages:
1: replacing previous import ‘golem::pkg_version’ by ‘pkgload::pkg_version’ when loading ‘MainExistingDatasets’ 
2: replacing previous import ‘golem::pkg_name’ by ‘pkgload::pkg_name’ when loading ‘MainExistingDatasets’ 
3: replacing previous import ‘golem::pkg_path’ by ‘pkgload::pkg_path’ when loading ‘MainExistingDatasets’ 

This PR addresses this issue by preventing the import of these three functions from {pkgload}.

[ColinFay]

@baptisteCD The new golem version is on its way to CRAN.

you might receive a message from the CRAN team in a few, so you might want to accept this PR soon :)

let me know if i can help you in any way

Cheers,
Colin