fix: remnant pyproject changes

Author: coroa

pyproject.toml

@@ -59,7 +59,7 @@ docs = [
     "nbsphinx-link==1.3.0",
     "docutils<0.21",
     "numpy<2",
-    "gurobipy>=13",
+    "gurobipy==11.0.2",
     "ipykernel==6.29.5",
     "matplotlib==3.9.1",
     "highspy>=1.7.1",
@@ -184,8 +184,3 @@ ignore = [
 [tool.ruff.lint.flake8-tidy-imports]
 # Disallow all relative imports.
 ban-relative-imports = "all"
-
-[dependency-groups]
-dev = [
-    "pypsa>=0.35.2",
-]