Fix test for forcetorque plugin on Windows

[GiacomoBisio]

The test fails with error:

 [INFO] |yarp.dev.PolyDriver|multipleanalogsensorsclient| Created device <multipleanalogsensorsclient>. See C++ class MultipleAnalogSensorsClient for documentation.
D:\a\gz-yarp-plugins\gz-yarp-plugins\tests\forcetorque\ForceTorqueTest.cc(44): error: The difference between measure(2) and -9.8*10 is 98, which exceeds 1e-2, where
measure(2) evaluates to 0,
-9.8*10 evaluates to -98, and
1e-2 evaluates to 0.01.
[INFO] |yarp.os.impl.PortCoreInputUnit|/ForceTorqueTest