[3006.x] Add cryptography back as a dependency for Salt 3006 to base.txt requirements

[dmurphy18]

What does this PR do?

Adds cryptography as a dependency to base.txt requirements. This will ensure that cryptography is installed as a dependency when pip installing salt, currently even though it is present in static ci and pkg, it is not installed as a dependency, unlike Salt 3007.x where it is. Salt 3007.x has cryptography as a dependency in base.txt and it was added to 3007 by PR 4de6b10, a Merge 3006.x to 3007.x (circa 7th Feb 2024), but it must have been between tagged versions of 3006 since it does not exist in any tagged version of 3006.x

What issues does this PR fix or reference?

Fixes #66883

Previous Behavior

cryptography failed to install as a dependency of Salt 3006 when pip installed.

New Behavior

cryptography now installs as a dependency of Salt 3006 when pip installed.

Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

• Docs
• Changelog - https://docs.saltproject.io/en/master/topics/development/changelog.html
• Tests written/updated

Commits signed with GPG?

Yes/No

Please review Salt's Contributing Guide for best practices, including the
PR Guidelines.

See GitHub's page on GPG signing for more information about signing commits with GPG.