doc: add libguestfs-xfs to test dependencies
doc: add libguestfs-xfs to test dependencies

Needed for virt-resize of XFS images

Closes #7399
mareklibra/cockpit,SotolitoLabs/cockpit,SotolitoLabs/cockpit,Scribery/cockpit,petervo/cockpit,xhad/cockpit,larskarlitski/cockpit,stefwalter/cockpit,petervo/cockpit,garrett/cockpit,Scribery/cockpit,michalskrivanek/cockpit,deryni/cockpit,Scribery/cockpit,cockpituous/cockpit,petervo/cockpit,Scribery/cockpit,larsu/cockpit,harishanand95/cockpit,michalskrivanek/cockpit,xhad/cockpit,xhad/cockpit,mareklibra/cockpit,cockpituous/cockpit,martinpitt/cockpit,deryni/cockpit,SotolitoLabs/cockpit,andreasn/cockpit,deryni/cockpit,cockpit-project/cockpit,stefwalter/cockpit,SotolitoLabs/cockpit,mvollmer/cockpit,mareklibra/cockpit,michalskrivanek/cockpit,deryni/cockpit,larsu/cockpit,stefwalter/cockpit,larskarlitski/cockpit,deryni/cockpit,mareklibra/cockpit,mareklibra/cockpit,SotolitoLabs/cockpit,larskarlitski/cockpit,harishanand95/cockpit,michalskrivanek/cockpit,harishanand95/cockpit,harishanand95/cockpit,stefwalter/cockpit,larsu/cockpit,larsu/cockpit,deryni/cockpit,moraleslazaro/cockpit,andreasn/cockpit,mvollmer/cockpit,michalskrivanek/cockpit,cockpit-project/cockpit,garrett/cockpit,moraleslazaro/cockpit,stefwalter/cockpit,cockpituous/cockpit,petervo/cockpit,Scribery/cockpit,garrett/cockpit,moraleslazaro/cockpit,mareklibra/cockpit,cockpit-project/cockpit,cockpituous/cockpit,harishanand95/cockpit,martinpitt/cockpit,andreasn/cockpit,michalskrivanek/cockpit,andreasn/cockpit,mareklibra/cockpit,stefwalter/cockpit,SotolitoLabs/cockpit,xhad/cockpit,cockpit-project/cockpit,larskarlitski/cockpit,andreasn/cockpit,andreasn/cockpit,mvollmer/cockpit,andreasn/cockpit,larskarlitski/cockpit,larsu/cockpit,mvollmer/cockpit,larskarlitski/cockpit,garrett/cockpit,moraleslazaro/cockpit,deryni/cockpit,stefwalter/cockpit,petervo/cockpit,xhad/cockpit,xhad/cockpit,SotolitoLabs/cockpit,cockpit-project/cockpit,petervo/cockpit,martinpitt/cockpit,garrett/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,Scribery/cockpit,harishanand95/cockpit,Scribery/cockpit,larskarlitski/cockpit,moraleslazaro/cockpit,xhad/cockpit,petervo/cockpit,larsu/cockpit,michalskrivanek/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,martinpitt/cockpit,mvollmer/cockpit,harishanand95/cockpit,martinpitt/cockpit