move volume fix into gstreamer provider, since its only provider specific

kivy/core/video/video_gstreamer.py

@@ -252,7 +252,7 @@ class VideoGStreamer(VideoBase):
     def _set_volume(self, volume):
         if self._audiosink is not None:
             self._volumesink.set_property('volume', volume)
-            self._volume = volume
+            self._volume = max(volume, .0000001)
 
     def _update(self, dt):
         if self._do_load:

kivy/uix/video.py

@@ -123,4 +123,4 @@ class Video(Image):
 
     def on_volume(self, instance, value):
         if self._video:
-            self._video.volume = max(value, .0000001)
+            self._video.volume = value