fix: remove deprecated dim parameter from linopy LinearExpression.groupby(...).sum() (#811)

* fix: remove deprecated dim parameter from linopy `LinearExpression.groupby(...).sum()` for compatibility with linopy > v0.9.0

* doc: add release note

---------

Co-authored-by: Thomas Gilon <thomas.gilon@openenergytransition.org>

Author: daniel-rdt

doc/release_notes.md

@@ -49,6 +49,8 @@
 
 * Remove unused `cba.methods` config option ([#805](https://github.com/open-energy-transition/open-tyndp/pull/805)).
 
+* Remove `dim` argument from `.groupby(...).sum()` call in DSR daily dispatch constraint as it is no longer accepted by linopy >= 0.9.0 and no longer needed since groupby-sum always reduces the grouped dimension ([#811](https://github.com/open-energy-transition/open-tyndp/pull/811)).
+
 **Documentation**
 
 * Update benchmarking documentation tables and figures for v0.7.1 ([#711](https://github.com/open-energy-transition/open-tyndp/pull/711)).

scripts/solve_network.py

@@ -1393,7 +1393,7 @@ def constrain_dsr_daily_dispatch(n: pypsa.Network, snapshots: pd.DatetimeIndex)
     )
 
     # calculate weighted daily energy
-    daily_energy = (p * weightings).groupby(day).sum(dim="snapshot")
+    daily_energy = (p * weightings).groupby(day).sum()
 
     # calculate daily energy limit using p_nom and pemmdb_hours
     rhs = xr.DataArray(