Tools: Install dbus-python on Linux only

tools/requirements/requirements.pytest.txt

@@ -14,5 +14,5 @@ scapy
 websocket-client
 netifaces
 rangehttpserver
-dbus-python; sys_platform != 'win32'
+dbus-python; sys_platform == 'linux'
 protobuf

tools/requirements/requirements.ttfw.txt

@@ -17,7 +17,7 @@ pygdbmi
 
 # ble
 future
-dbus-python; sys_platform != 'win32'
+dbus-python; sys_platform == 'linux'
 pygobject; sys_platform != 'win32'
 
 # iperf_test_util