Create SECURITY.md

[nathanshammah]

Create security policy document with basic info.

Description

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License

• I license this contribution under the terms of the GNU GPL, version 3 and grant Unitary Fund the right to provide additional permissions as described in section 7 of the GNU GPL, version 3.

Before opening the PR, please ensure you have completed the following where appropriate.

• I added unit tests for new code.
• I used type hints in function signatures.
• I used Google-style docstrings for functions.
• I updated the documentation where relevant.
• Added myself / the copyright holder to the AUTHORS file

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (68af75d) 98.20% compared to head (732e533) 98.26%.
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2162      +/-   ##
==========================================
+ Coverage   98.20%   98.26%   +0.06%     
==========================================
  Files          88       88              
  Lines        4170     4146      -24     
==========================================
- Hits         4095     4074      -21     
+ Misses         75       72       -3     

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[natestemen]

Thanks Nathan! All looks good from my POV, would just ask that we don't use the "bug report" template for security related issues. We should either link to https://github.com/unitaryfund/mitiq/issues/new to create a new empty issue, or create a security issue template. WDYT?

[Misty-W]

Echo the issue template comment. Otherwise looks good!

[nathanshammah]

Thanks @Misty-W @natestemen, agreed!