Add minor fix

[davide-f]

Closes # (if applicable).

Changes proposed in this Pull Request

There are 3 redundant lines in the geothermal modelling.
These lines change the efficiency of the link but the same efficiency is already specified see:

pypsa-eur/scripts/prepare_sector_network.py

Lines 4463 to 4473 in 2e07e82

	n.add(
	"Link",
	bus + " geothermal organic rankine cycle",
	bus0=f"{bus} geothermal heat surface",
	bus1=bus,
	p_nom_extendable=True,
	carrier="geothermal organic rankine cycle",
	capital_cost=orc_capital_cost * efficiency_orc,
	efficiency=efficiency_orc,
	lifetime=costs.at["organic rankine cycle", "lifetime"],
	)

Checklist

• I tested my contribution locally and it works as intended.
• Code and workflow changes are sufficiently documented.
• Changed dependencies are added to envs/environment.yaml.
• Changes in configuration options are added in config/config.default.yaml.
• Changes in configuration options are documented in doc/configtables/*.csv.
• Sources of newly added data are documented in doc/data_sources.rst.
• A release note doc/release_notes.rst is added.

[lkstrp]

Thank you @davide-f !