chore: bump version to 1.8.0

[devonakelley]

Version bump to 1.8.0 for PyPI release.

Changes since 1.7.0

#121 — kalibr init HuggingFace support

• Scanner detects all 17 HF InferenceClient task methods + pipeline()
• Rewriter generates router.execute() with task-appropriate model pairs
• router.execute() task_method_map covers all 17 PATCHED_METHODS (was 10)
• All scaffolded Routers now include 2 default paths (Thompson Sampling works from day one)
• import kalibr enforced as first line in all generated code

#123 — HF token + DeepSeek provider

• HF_API_TOKEN / HUGGING_FACE_HUB_TOKEN passed to InferenceClient
• deepseek-* models routed correctly via _call_deepseek() instead of falling through to OpenAI

#124 — DeepSeek pricing + vendor attribution

• DeepSeek added to pricing.py (V3, R1, Coder at correct rates)
• OpenAI instrumentor detects DeepSeek by model prefix, sets correct llm.vendor and cost