install: update and document new dependencies

docs/installation.md

@@ -29,6 +29,10 @@ The Debian/Ubuntu packages that need to be installed are
 in Fedora you need `gtk3` and `python3-gobject`;
 if you're using another
 distribution the required packages are most likely named something similar.
+The Solaar GUI also requires Python packages
+`PyYAML` (>= 5.1), `python-xlib` (>= 0.27), `pynput` (>= 1.7.0), and `pustil` (>= 5.7.3).
+These are best installed using `pip` via `pip install --user <package>`
+if they are not already available.
 
 If desktop notifications bindings are also installed
 (`gir1.2-notify-0.7` for Debian/Ubuntu),

setup.py

@@ -60,6 +60,10 @@ battery status, and show and modify some of the modifiable features of devices.
     python_requires='>=3.6',
     install_requires=[
         'pyudev (>= 0.13)',
+        'PyYAML (>= 5.1)',
+        'python-xlib (>= 0.27)',
+        'pynput (>= 1.7.0)',
+        'psutil (>= 5.7.3)',
     ],
     package_dir={'': 'lib'},
     packages=['hidapi', 'logitech_receiver', 'solaar', 'solaar.ui', 'solaar.cli'],