Allow skipping tls verification

[spicyneuron]

Local endpoints may be deployed with self-signed certificates, which Python rejects.

This PR adds an opt-in way to skip validation, following the existing patterns. Default behavior remains unchanged.

(Copy of #32, simply moved into a separate branch)

[chr15m]

I did some research and apparently this can be accomplished with the following built in Python env vars.

Disable Python's HTTPS verification globally:

PYTHONHTTPSVERIFY=0 ./runprompt hello.prompt

Trust a specific self-signed certificate:

SSL_CERT_FILE=/path/to/custom-ca.pem ./runprompt hello.prompt

I'd be happy to add these examples to the README.md - I'm a bit hesitant to duplicate this functionality inside runprompt itself. Is there some reason why it would be better to have it in runprompt?

[spicyneuron]

PYTHONHTTPSVERIFY=0 would work for the requests library, but you're using urllib.request.urlopen(), which is controlled by ssl.SSLContext. No global off switch for ssl, AFAIK.

SSL_CERT_FILE would probably work, but requires cert pinning on every client. That's the exactly hassle I'm trying to avoid by not verifying. No hard feelings if you prefer not supporting this; I'm fine using my fork regardless.

[chr15m]

I have a much smaller patch for this:

    if get_conf("insecure"):
        import ssl
        ssl._create_default_https_context = ssl._create_unverified_context

[spicyneuron]

@chr15m Good catch. Updated!