Fix passing path to C code

pycrystfel/bindings.pyx

+import os
+
 from . cimport crystfel
 
 def progress_bar(val, total, text):
@@ -5,6 +7,6 @@ def progress_bar(val, total, text):
 
 def inspect_geom_file(path):
     cdef crystfel.detector *det
-    det = crystfel.get_detector_geometry(path, NULL)
+    det = crystfel.get_detector_geometry(os.fsencode(path), NULL)
     print("n_panels:", det.n_panels)
     print("panel names:", [det.panels[i].name for i in range(det.n_panels)])