chore: bump builder base image to Python 3.14

[Pymetheus]

Description

Update docker/Dockerfile to use ghcr.io/astral-sh/uv:python3.14-bookworm-slim instead of the previous python3.12 tag to adopt Python 3.14 (newer features and security fixes). No other Dockerfile changes were made.

Type of Change

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

Related Issue

Dependabot only bumped 3.12-slim-bookworm to 3.14-slim-bookworm, leading to a failed Build Docker Image & Smoke Test job in #20

Changes Made

• Update docker/Dockerfile to use ghcr.io/astral-sh/uv:python3.14-bookworm-slim instead of the previous python3.12

Testing

Describe how you tested your changes:

• Unit tests pass
• Integration tests pass
• Manual testing performed

Screenshots (if applicable)

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Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have updated the documentation accordingly
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

Additional Context

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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