ddev fails to start on corp network

[gioccher]

Additional environment details (Operating System, Cloud provider, etc):
macOS 14.3.1
netskope traffic inspection

Steps to reproduce the issue:

1. follow instructions on https://docs.datadoghq.com/developers/integrations/python/?tab=macos
2. run ddev --version

Describe the results you received:

Error: download failed: https://github.com/indygreg/python-build-standalone/releases/download/20230826/cpython-3.11.5%2B20230826-aarch64-apple-darwin-install_only.tar.gz

Caused by:
    0: error sending request for url (https://github.com/indygreg/python-build-standalone/releases/download/20230826/cpython-3.11.5%2B20230826-aarch64-apple-darwin-install_only.tar.gz): error trying to connect: invalid peer certificate: UnknownIssuer
    1: error trying to connect: invalid peer certificate: UnknownIssuer
    2: invalid peer certificate: UnknownIssuer

Describe the results you expected:
ddev shows its version number

Additional information you deem important (e.g. issue happens only occasionally):
Our corporate proxy inspects traffic and thus inserts its own CA certificate that has to be configured to trust across applications on the system. I do this by setting REQUESTS_CA_BUNDLE and SSL_CERT_FILE, etc. It seems that ddev doesn't respect either of those. Is there another environment variable that it takes into account?
Also, it looks like ddev is trying to download and install python, but python 3.11 is already installed on the system.

% which python3.11
/opt/homebrew/bin/python3.11
% python3.11 --version
Python 3.11.9