Fix gh-6566. Update the pictures in the convolution tutorial.

a9940758 · Frederic Bastien · b2fdd67a · b2fdd67a · a9940758 · a9940758
--- a/doc/tutorial/conv_arithmetic_figures/padding_strides_odd_transposed.gif
+++ b/doc/tutorial/conv_arithmetic_figures/padding_strides_odd_transposed.gif
--- a/doc/tutorial/conv_arithmetic_figures/padding_strides_odd_transposed.pdf
+++ b/doc/tutorial/conv_arithmetic_figures/padding_strides_odd_transposed.pdf