bump code version in zenodo ref

Author: navidcy

README.md

@@ -102,7 +102,7 @@ and [Navid C. Constantinou][] (@navidcy).
 
 The code is citable via [zenodo](https://zenodo.org). Please cite as:
 
-> Navid C. Constantinou & Gregory L. Wagner. (2021). FourierFlows/FourierFlows.jl: FourierFlows v0.8.0 (Version v0.8.0). Zenodo.  [http://doi.org/10.5281/zenodo.1161724](http://doi.org/10.5281/zenodo.1161724)
+> Navid C. Constantinou & Gregory L. Wagner and co-contributors. (2021). FourierFlows/FourierFlows.jl: FourierFlows v0.9.0 (Version v0.9.0). Zenodo.  [http://doi.org/10.5281/zenodo.1161724](http://doi.org/10.5281/zenodo.1161724)
 
 
 ## Contributing