Add validation for pypi package

What does this MR do?

Description

The PyPI package version does not have validation when a new package is persisted in the database. This MR solves this issue by adding active record validations to the version when a PyPI package is created.

Proposed solution

Following the suggestion and possible regexp in #214429 (closed) with the version format in the pypi version doc.

The regex currently been used is from the doc, which allows more versions that the canonical version.

          \A(?:
            v?
            (?:([0-9]+)!)?                                                 (?# epoch)
            ([0-9]+(?:\.[0-9]+)*)                                          (?# release segment)
            ([-_\.]?((a|b|c|rc|alpha|beta|pre|preview))[-_\.]?([0-9]+)?)?  (?# pre-release)
            ((?:-([0-9]+))|(?:[-_\.]?(post|rev|r)[-_\.]?([0-9]+)?))?       (?# post release)
            ([-_\.]?(dev)[-_\.]?([0-9]+)?)?                                (?# dev release)
            (?:\+([a-z0-9]+(?:[-_\.][a-z0-9]+)*))?                         (?# local version)
            )\z}xi

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team