Remove SECURITY.md to rely on organization-wide community health file

[d33bs]

Description

This PR removes the repository specific SECURITY.md file to rely on the organization-wide community health file (provided here as a result of cytomining/.github#6). After this file is removed in the CytoTable repository, GitHub will provide automatic integration of the details in the sidebar and within the "root" view of the repository (via the tabs above the README.md display).

Thanks for any comments or feedback you may have!

What is the nature of your change?

• Bug fix (fixes an issue).
• Enhancement (adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).
• This change requires a documentation update.

Checklist

Please ensure that all boxes are checked before indicating that a pull request is ready for review.

• I have read the CONTRIBUTING.md guidelines.
• My code follows the style guidelines of this project.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• New and existing unit tests pass locally with my changes.
• I have added tests that prove my fix is effective or that my feature works.
• I have deleted all non-relevant text in this pull request template.

[d33bs]

Thanks @kenibrewer ! Merging this in.