Adding zip_safe flag to setuptools prevent "module references __file__" warnings

[phutelmyer]

Describe the change
Referenced in #249, the following warnings were thrown upon build:

docker-compose build

...

strelka.tests.__pycache__.test_scan_docx.cpython-310: module references __file__
strelka.tests.__pycache__.test_scan_gif.cpython-310: module references __file__
strelka.tests.__pycache__.test_scan_html.cpython-310: module references __file__
strelka.tests.__pycache__.test_scan_iso.cpython-310: module references __file__
strelka.tests.__pycache__.test_scan_jpeg.cpython-310: module references __file__
strelka.tests.__pycache__.test_scan_msi.cpython-310: module references __file__
strelka.tests.__pycache__.test_scan_pe.cpython-310: module references __file__
strelka.tests.__pycache__.test_scan_png_eof.cpython-310: module references __file__
strelka.tests.__pycache__.test_scan_vhd.cpython-310: module references __file__

...

These warning messages indicate that the package contains Python modules that reference the special variable __file__. The __file__ variable is a built-in variable that holds the name of the file that the currently executing code is located in.

When a Python module references the __file__ variable, setuptools will emit a warning message to inform you that the module may not work correctly when the package is installed as a zip file. This is because the file variable will not contain the correct value when the module is executed from within a zip file.
This warning can be silenced by adding zip_safe=True to setuptools.py

import setuptools

setuptools.setup(
    name='strelka',
    author='Target Brands, Inc.',
    description='strelka: container-based file analysis at scale',
    license='Apache 2.0',
    packages=setuptools.find_packages(),
    scripts=['bin/strelka-backend'],
    zip_safe=True
)

This flag has been added to the project's setuptools.py files, although is really only necessary for the Backend.

Describe testing procedures
Added flag and rebuilt without a cache.

Sample output
N/A

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of and tested my 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