Fix Missing pyproject.toml Deps, Breaking Release PyPi Workflow & Add Build Wheel / SDist Check to PR Workflow

[lapp0]

Fixes #934

Problem

• Release to PyPi failed for v0.0.42 because pycountry and pyairports wasn't in pyproject.toml required dependencies
• We merged code which caused this failure without detecting it.

Solution

• Add pycountry and pyairports to pyproject.toml required dependencies
• Add Test SDist and Build Wheel to PR Test Suite

Example: failing workflow without pycountry and pyairports

• https://github.com/lapp0/outlines/actions/runs/9332636096/job/25688717515

Example: Release to PyPi using new workflow, works up to the point it 403s. I expect it to release provided a correct pypi token, but I can smoke test first if you prefer.

• https://github.com/lapp0/outlines/actions/runs/9333098031/job/25689734009