feat: update ConvMixer to support reactant #254

Job	Run time
downgrade	1h 13m 14s
test (1, ubuntu-latest, conv, default, true)	34m 34s
test (1, ubuntu-latest, dense, default, true)	23m 41s
test (1, ubuntu-latest, normalization, default, true)	52m 24s
test (1, ubuntu-latest, misc, default, true)	41m 46s
test (1, ubuntu-latest, dense, default, false)	20m 35s
test (1, ubuntu-latest, misc, default, false)	36m 35s
test (1, macos-latest, all, default, true)	1h 12m 25s
test (1, windows-latest, all, default, true)	1h 8m 59s
	7h 4m 13s

Provide feedback