uv

b873e3e9 - Support environment variables in index URLs in requirements files (#2036)

Support environment variables in index URLs in requirements files (#2036) ## Summary This also preserves the environment variables in the output file, e.g.: ``` Resolved 1 package in 216ms # This file was autogenerated by uv via the following command: # uv pip compile requirements.in --emit-index-url --index-url https://test.pypi.org/${SUFFIX} requests==2.5.4.1 ``` I'm torn on whether that's correct or undesirable here. Closes #2035.