contrib: Skip vagrant authors in extract_authors
contrib: Skip vagrant authors in extract_authors

Authors in the git log who have used the vagrant VM have always been
repeat contributors who have resolved invalid git authorship issues in
subsequent submissions, so there is no need to take these authors into
account when calculating the authors list.

Signed-off-by: Joe Stringer <16a9a54ddf4259952e3c118c763138e83693d7fd@cilium.io>

cilium/cilium,cilium/cilium,tklauser/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium/cilium,michi-covalent/cilium,cilium/cilium,cilium/cilium,tklauser/cilium,tklauser/cilium,tklauser/cilium,tklauser/cilium,michi-covalent/cilium,michi-covalent/cilium