fix mpl warning

Author: nschloe

README.md

@@ -1,6 +1,6 @@
 <p align="center">
   <a href="https://github.com/nschloe/tikzplotlib"><img alt="tikzplotlib" src="https://nschloe.github.io/tikzplotlib/logo-tikzplotlib.svg" width="60%"></a>
-  <p align="center">The artist formerly known as _matplotlib2tikz._</p>
+  <p align="center">The artist formerly known as *matplotlib2tikz.*</p>
 </p>
 
 [![CircleCI](https://img.shields.io/circleci/project/github/nschloe/tikzplotlib/master.svg?style=flat-square)](https://circleci.com/gh/nschloe/tikzplotlib/tree/master)

tikzplotlib/_axes.py

@@ -208,12 +208,18 @@ def _ticks(self, data, obj):
         )
         self.axis_options.extend(
             _get_ticks(
-                data, "minor x", obj.get_xticks("minor"), obj.get_xticklabels("minor")
+                data,
+                "minor x",
+                obj.get_xticks(minor=True),
+                obj.get_xticklabels(minor=True),
             )
         )
         self.axis_options.extend(
             _get_ticks(
-                data, "minor y", obj.get_yticks("minor"), obj.get_yticklabels("minor")
+                data,
+                "minor y",
+                obj.get_yticks(minor=True),
+                obj.get_yticklabels(minor=True),
             )
         )