Load cookies from browser (#2040)

setup.py

@@ -22,6 +22,9 @@ if sys.version_info < (3, 8):
     sys.exit('Instaloader requires Python >= 3.8.')
 
 requirements = ['requests>=2.4']
+optional_requirements = {
+    'browser_cookie3': ['browser_cookie3>=0.19.1'],
+}
 
 keywords = (['instagram', 'instagram-scraper', 'instagram-client', 'instagram-feed', 'downloader', 'videos', 'photos',
              'pictures', 'instagram-user-photos', 'instagram-photos', 'instagram-metadata', 'instagram-downloader',
@@ -44,6 +47,7 @@ setup(
     long_description=open(os.path.join(SRC, 'README.rst')).read(),
     install_requires=requirements,
     python_requires='>=3.8',
+    extras_require=optional_requirements,
     entry_points={'console_scripts': ['instaloader=instaloader.__main__:main']},
     zip_safe=False,
     keywords=keywords,