It's used only as a dev dependency in 4 crates.

Depender (with downloads and own rev deps) strict_encoding_test version
1.0K 10 psbt dev ^0.9.0
200 2 lnpbp_chain dev ^0.9.0
130 26 internet2 dev ^0.9.0
1 lnp_node dev ^0.9.0