Update @michaelgrund's affiliation in AUTHORS.md (#899)

Author: michaelgrund

AUTHORS.md

@@ -12,7 +12,7 @@ The following people have contributed code and/or documentation to the project
 * [Leonardo Uieda](http://www.leouieda.com/) | [0000-0001-6123-9515](https://orcid.org/0000-0001-6123-9515) | Department of Earth, Ocean and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
 * [Liam Toney](https://liam.earth/) | [0000-0003-0167-9433](https://orcid.org/0000-0003-0167-9433) | Alaska Volcano Observatory and Wilson Alaska Technical Center, Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USA
 * [Malte Ziebarth](https://github.com/mjziebarth) | [0000-0002-5190-4478](https://orcid.org/0000-0002-5190-4478) | GFZ German Research Centre for Geosciences, Potsdam, Germany
-* [Michael Grund](https://github.com/michaelgrund) | [0000-0001-8759-2018](https://orcid.org/0000-0001-8759-2018)
+* [Michael Grund](https://github.com/michaelgrund) | [0000-0001-8759-2018](https://orcid.org/0000-0001-8759-2018) | Innoplexia GmbH, Heidelberg, Germany
 * [Tyler Newton](http://www.tnewton.com/) | [0000-0002-1560-6553](https://orcid.org/0000-0002-1560-6553) | Department of Earth Sciences, University of Oregon, Eugene, OR, USA
 * [Wei Ji Leong](https://github.com/weiji14) | [0000-0003-2354-1988](https://orcid.org/0000-0003-2354-1988) | Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand
 * [William Schlitzer](https://github.com/willschlitzer) | [0000-0002-5843-2282](https://orcid.org/0000-0002-5843-2282) | Unaffiliated