fix: pin pypsa<1.1

Author: lkstrp

pixi.lock

@@ -82,7 +82,7 @@ pre-commit = ">=4.3.0"
 proj = ">=9.6.2"
 pylint = ">=4.0.2"
 pydeck = ">0.6"  # pypsa fails to import with pydeck <0.6, lower bound was only added from pypsa 1.0.6
-pypsa = ">=0.35.2"
+pypsa = "<1.1"
 pyscipopt = ">=5.6.0"
 pytables = ">=3.10.2"
 python = ">=3.10"