Fix missing PyBluez dependency

The code imports 'bluetooth._bluetooth' which requires the PyBluez package
(not bluepy). PyBluez provides Classic Bluetooth support needed by utils.py
and sensor_reader.py.

- Add pybluez>=0.31 to both requirements.txt and pyproject.toml
- Keep bluepy and paho-mqtt as they are also needed
- bluez system package also needed (already in debian/control)

Fixes: ModuleNotFoundError: No module named 'bluetooth'

pyproject.toml

@@ -26,6 +26,7 @@ classifiers = [
 ]
 
 dependencies = [
+    "pybluez>=0.31",
     "bluepy>=1.3.0",
     "paho-mqtt>=1.6.0",
 ]

requirements.txt

@@ -1,2 +1,3 @@
+pybluez
 bluepy
 paho-mqtt