(GH-1057) Regex fix to allow dotted resources

(GH-1057) Regex fix to allow dotted resources

Prior to this commit, one of our recent module updates introduced a
regex validation step for the resource names in our ppa.pp manifest
which would raise an issue if a valid resource name contained a dot (.).

This commit aims to slightly adjust the regex validation so that it
allows for dotted resource names. This PR should fix issue #1057.