exclude buggy ppm version

Author: lindnemi

envs/environment.yaml

@@ -20,7 +20,7 @@ dependencies:
 - pypsa>= 0.32.1
 - atlite>=0.3
 - linopy>=0.4.4
-- powerplantmatching>=0.5.15
+- powerplantmatching>=0.5.15,<0.7 # restrict ppm until fix of https://github.com/PyPSA/powerplantmatching/issues/229
 
 # Dependencies of the workflow itself
 - dask