Add requirements for SAML SSO

[Wellyas]

Related Issue: None

New Behavior

Extends requirements to enable the use of SAML SSO Providers from Python Social Auth.

Contrast to Current Behavior

Currently these dependencies aren't included, meaning users can't take advantage of SAMLSSO unless they create their own image.

Discussion: Benefits and Drawbacks

• Benefit: Enabling users to use functionality included in Netbox without needing to create bespoke images and SAML is more use than OICD in the enterprise world.
• Drawback: Additional dependencies increase the image size, and the version pinning will need to be periodically reviewed. The build of the image will take more time because of the need to build python3-saml and the cryptography python package.
• Backwards-compatible: Yes

Changes to the Wiki

None

Proposed Release Note Entry

Requirements needed to use SAML SSO Providers have been added

Double Check

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• I have explained my PR according to the information in the comments.
• My PR targets the develop branch.