fix subsidy module

[irr-github]

Description

Make subsidies year dependent

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Performance improvement
• Code refactoring
• Dependencies update

Related Issues

Subsidies only applied to newbuilds

Changes Made

• subsidies now also applied to brownfield generators (moved to solve_network until refactor electricity)
• subsidies now year dependent per carrier

Testing

• Tests pass locally
• Added new tests for the changes
• Updated existing tests
• No tests needed (documentation only)

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have updated the CHANGELOG.md file
• Any dependent changes have been merged and published

Screenshots (if applicable)

Additional Notes