setup.py: install optional modules. fixes #3927

setup.py

@@ -42,9 +42,6 @@ setup(
     name="Electrum",
     version=version.ELECTRUM_VERSION,
     install_requires=requirements,
-    extras_require={
-        'hardware': requirements_hw,
-    },
     packages=[
         'electrum',
         'electrum_gui',
@@ -89,3 +86,8 @@ setup(
     url="https://electrum.org",
     long_description="""Lightweight Bitcoin Wallet"""
 )
+
+# Optional modules (not required to run Electrum)
+import pip
+opt_modules = requirements_hw + ['pycryptodomex']
+[ pip.main(['install', m]) for m in opt_modules ]