Fix typo.

xfel_calibrate/calibrate.py

@@ -251,7 +251,7 @@ elif len(sys.argv) >= 3:
                             and p.name != cvar)
 
                 # This may be not a public API
-                # May requir reprogramming in case of argparse updates
+                # May require reprogramming in case of argparse updates
                 pars_group = parser._action_groups[2 if required else 1]
 
                 default = p.value if (not required) else None