Load pins from iree-requirements.txt in setup.py.

[ScottTodd]

Without this, pip installs require the unqualified iree-compiler package.
With this, pip installs require the iree-compiler>=[version pin] package (note that get_version_spec here is inserting the >=, even if the requirements file has ==)

This helps for https://github.com/nod-ai/sharktank/tree/main?tab=readme-ov-file#install-development-packages with these instructions:

# Clone and install editable iree-turbine dep in deps/
pip install -f https://iree.dev/pip-release-links.html --src deps \
  -e "git+https://github.com/iree-org/iree-turbine.git#egg=shark-turbine"

[ScottTodd]

Not sure how to make this work without either

A) adding --find-links https://iree.dev/pip-release-links.html to all install commands for iree-turbine
B) only pinning to versions here that are published to pypi (https://pypi.org/project/iree-compiler/#history)

[ScottTodd]

Closing this since it's stale.