so i am back to the problem in the original post. my pex depends on ipdb, but when I add it to requiremens.txt, I get this error, even though ipdb is definitely on https://pypi.org/simple/ipdb/ with a version suitable for python 3.10

stderr:
pid 75041 -> /Users/maheshvashishtha/.cache/pants/named_caches/pex_root/venvs/c9e55cc98846b062ba9676b3c1a5214512602544/07b01ddf09672a6b76d4e76683b2604821a7fda1/bin/python -sE /Users/maheshvashishtha/.cache/pants/named_caches/pex_root/venvs/c9e55cc98846b062ba9676b3c1a5214512602544/07b01ddf09672a6b76d4e76683b2604821a7fda1/pex --disable-pip-version-check --no-python-version-warning --exists-action a --no-input --isolated -q --cache-dir /Users/maheshvashishtha/.cache/pants/named_caches/pex_root/pip_cache --log /private/var/folders/ts/7lr9hnf958b68z7qr4dvtqvh0000gn/T/pants-sandbox-nBWpPv/.tmp/pex-pip-log.9lc3m4zm/pip.log download --dest /Users/maheshvashishtha/.cache/pants/named_caches/pex_root/downloads/resolver_download.w2d38tzk/cp39-cp39-manylinux2014_x86_64 --only-binary :all: fsspec[http] ipdb lz4==4.0.2 modin@ git+<https://github.com/devin-petersohn/modin.git@service/init-prod> rpyc==5.2.3 segment-analytics-python==2.2.1 snowflake-connector-python[pandas]==2.7.11 --platform manylinux2014_x86_64 --implementation cp --python-version 39 --abi cp39 --index-url <https://pypi.org/simple/> --retries 5 --timeout 15 exited with 1 and STDERR:
ERROR: Could not find a version that satisfies the requirement ipdb
ERROR: No matching distribution found for ipdb