[MovingWindow] Don't filter out None values from resampler

The resampler sends `None` values when there is no source data.  In
this case, the values need to be sent to the buffer, so that it can
update its gaps immediately, instead of waiting until when data is
finally available.

Signed-off-by: Sahas Subramanian <[email protected]>

Author: shsms

src/frequenz/sdk/timeseries/_moving_window.py

@@ -343,8 +343,7 @@ def _configure_resampler(self) -> None:
         assert self._resampler is not None
 
         async def sink_buffer(sample: Sample[Quantity]) -> None:
-            if sample.value is not None:
-                self._buffer.update(sample)
+            self._buffer.update(sample)
 
         resampler_channel = Broadcast[Sample[Quantity]](name="average")
         self._resampler_sender = resampler_channel.new_sender()