Allow custom CA_BUNDLE via SDC_SSL_VERIFY env

[DaveCanHaz]

This will allow for a custom CA_BUNDLE to be provided via an environment variable. Prior to this change the only valid values for the SDC_SSL_VERIFY env variable were True, and anything else was evaluated to False. For example:

Prior to this change:

Value	Result
SDC_SSL_VERIFY=true	ssl_verify=True
SDC_SSL_VERIFY=false	ssl_verify=False
SDC_SSL_VERIFY=/path/to/custom.pem	ssl_verify=False

After this change implemented:

Value	Result
SDC_SSL_VERIFY=true	ssl_verify=True
SDC_SSL_VERIFY=false	ssl_verify=False
SDC_SSL_VERIFY=/path/to/custom.pem	ssl_verify=/path/to/custom.pem

[tembleking]

Hi @DaveCanHaz, unfortunately the tests cannot be run against PRs from forks of the project, because there's a limitation in GitHub Actions where the secrets are not transfered to the runner.

The content of the PR looks good to me tho, so I am going to merge it anyway.

Thank you for your contribution!

[DaveCanHaz]

@tembleking - Understood and Thanks! Let me know if there is a more preferred mechanism for submitting PRs / changes in the future.

Kindly, when is PyPI update expected with the latest changes?