PR: Add new security policy

[CAM-Gerlach]

Adds a security policy following our standard org guidelines

[CAM-Gerlach]

Looks like the async test is failing on some platforms with this issue:

 FAILED qtconsole/tests/test_inprocess_kernel.py::test_execute - Failed: async def functions are not natively supported.
You need to install a suitable plugin for your async framework, for example:
  - anyio
  - pytest-asyncio
  - pytest-tornasync
  - pytest-trio
  - pytest-twisted

[ccordoba12]

@dalthviz, please take a look at the problem mentioned by @CAM-Gerlach in another PR.

[ccordoba12]

Thanks @CAM-Gerlach!

[CAM-Gerlach]

@dalthviz, please take a look at the problem mentioned by @CAM-Gerlach in another PR.

(Opened as issue #634 for reference)