feat: Build and publish Helm chart in CI

[lewisjared]

Description

Checklist

Please confirm that this pull request has done the following:

• Tests added
• Documentation added (where applicable)
• Changelog item added to changelog/

[codecov]

Codecov Report

❌ Patch coverage is 35.13514% with 24 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...kages/climate-ref-core/src/climate_ref_core/env.py	5.26%	18 Missing ⚠️
...climate-ref-core/src/climate_ref_core/providers.py	53.84%	4 Missing and 2 partials ⚠️

Files with missing lines	Coverage Δ
...f-celery/src/climate_ref_celery/celeryconf/base.py	100.00% <100.00%> (ø)
...kages/climate-ref/src/climate_ref/cli/providers.py	79.06% <100.00%> (ø)
packages/climate-ref/src/climate_ref/testing.py	92.30% <ø> (-0.15%)	⬇️
...climate-ref-core/src/climate_ref_core/providers.py	89.88% <53.84%> (-1.13%)	⬇️
...kages/climate-ref-core/src/climate_ref_core/env.py	40.00% <5.26%> (-60.00%)	⬇️

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[lewisjared]

I don't see a service named celery-metrics-service. Should this be the flower service?