Pass MDAnalysis str() obj instead of Path for PDB reader

mrdna/readers/segmentmodel_from_pdb.py

@@ -29,7 +29,7 @@ bases = resnames.keys()
 resname_to_key = {n:k for k,v in resnames.items() for n in v.split()}
 complement = dict(A='T', C='G', T='A', G='C')
 
-refUnis = {b:mda.Universe(get_resource_path("generate-nts/1-w3dna/{}{}.pdb".format(b,complement[b])))
+refUnis = {b:mda.Universe(str(get_resource_path("generate-nts/1-w3dna/{}{}.pdb".format(b,complement[b]))))
            for b in bases}
 
 stack_text = "not name O5' P O1P O2P OP1 OP2 O3' 1H* 2H* 3H* 0H* H*"