Move NBVAL to dev dependencies

Author: danielfeismann

CHANGELOG.md

@@ -11,6 +11,7 @@ All notable changes to this project will be documented in this file.
 - Using `NBVAL` as validation for jupyter notebooks [#351](https://github.com/ie3-institute/pypsdm/issues/351) 
 
 ### Changed
+- Move `NBVAL` to dev dependencies [#374](https://github.com/ie3-institute/pypsdm/issues/374)
 
 ### Removed
 - Removed duplicated code within `plots.grid` [#346](https://github.com/ie3-institute/pypsdm/issues/346)