Adjusted excel columns for PTES

[cpschau]

Changes proposed in this Pull Request

This PR updates the DEA Excel columns (including uncertainty lookup) for pit thermal energy storage indexed in compile_cost_assumptions. As a result, capital cost and FOM values were adjusted in the cost files for 2045 and 2050.

Checklist

• Code changes are sufficiently documented; i.e. new functions contain docstrings and further explanations may be given in doc.
• Data source for new technologies is clearly stated.
• Newly introduced dependencies are added to environment.yaml (if applicable).
• A note for the release notes doc/release_notes.rst of the upcoming release is included.
• I consent to the release of this PR's code under the GPLv3 license.

[TomKae00]

Looks good to me!