use psutil for cpu temp (#200)

src/rpi-cpu2mqtt.py

@@ -160,14 +160,16 @@ def read_ext_sensors():
 
 
 def check_cpu_temp():
-    full_cmd = f"awk '{{printf (\"%.2f\\n\", $1/1000); }}' $(for zone in /sys/class/thermal/thermal_zone*/; do grep -iq \"{config.cpu_thermal_zone}\" \"${{zone}}type\" && echo \"${{zone}}temp\"; done)"    
     try:
-        p = subprocess.Popen(full_cmd, shell=True, stdout=subprocess.PIPE).communicate()[0]
-        cpu_temp = p.decode("utf-8").strip().replace(",", ".")
-    except Exception:
-        cpu_temp = None if config.use_availability else 0
-
-    return cpu_temp
+        temps = psutil.sensors_temperatures()
+        if not temps or "coretemp" not in temps:
+            raise ValueError("CPU temperature sensor not found.")
+        
+        cpu_temp = temps["coretemp"][0].current
+        return round(cpu_temp, 2)
+    except Exception as e:
+        print(f"Error reading CPU temperature: {e}")
+        return None if config.use_availability else 0
 
 
 def check_sys_clock_speed():