Felix Thielke

Fixed Conv3DTranspose with strides for data format channels_first (fixes #1714)

1

While shape calculations for the input correctly distinguished between channels_first and channels_last, shape calculations for the inputs of the final Slice and Pad nodes always assumed channels_last format.

Conv3DTranspose with strides leads to wrong output dimensions if data format is channels_first

2

**Describe the bug** When converting a model containing Conv3DTranspose with strides > 1 and data_format='channes_first', the output of the resulting ONNX model has the wrong shape (seems to be off...