Set python_min to 3.8 and remove runtime dep on opencv

[weiji14]

Patches #59 with the following changes:

• Set python_min and change to pypi.org url to satisfy linter - sahi v0.11.19 #59 (comment)
• Remove opencv and numpy<2 pin following sahi v0.11.18 #58 (comment)

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[conda-forge-admin]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe/meta.yaml) and found it was in an excellent condition.

[weiji14]

Getting this error on import sahi:

import: 'sahi'
Traceback (most recent call last):
  File "/home/conda/feedstock_root/build_artifacts/sahi_1732418500825/test_tmp/run_test.py", line 2, in <module>
    import sahi
  File "/home/conda/feedstock_root/build_artifacts/sahi_1732418500825/_test_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_p/lib/python3.7/site-packages/sahi/__init__.py", line 3, in <module>
    from sahi.annotation import BoundingBox, Category, Mask
  File "/home/conda/feedstock_root/build_artifacts/sahi_1732418500825/_test_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_p/lib/python3.7/site-packages/sahi/annotation.py", line 9, in <module>
    from sahi.utils.coco import CocoAnnotation, CocoPrediction
  File "/home/conda/feedstock_root/build_artifacts/sahi_1732418500825/_test_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_p/lib/python3.7/site-packages/sahi/utils/coco.py", line 17, in <module>
    from shapely import GeometryCollection, MultiPolygon, Polygon
ImportError: cannot import name 'GeometryCollection' from 'shapely' (/home/conda/feedstock_root/build_artifacts/sahi_1732418500825/_test_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_p/lib/python3.7/site-packages/shapely/__init__.py)

Looks like this was mentioned at obss/sahi#1061 (comment) that shapely>=2.0 is required.

[weiji14]

Note: Also pinning python>3.8 because shapely=2.0.0 on conda-forge only has Python 3.8+ builds (on PyPI, shapely=2.0.0 has Python 3.7 wheels).