pin back testify to v1.7

fix: nullable slice generation (hamba#176)

chore: remove depreciated ioutil package (hamba#171)

feat: add schema reference support (hamba#160)

feat: allow deflate compression level (hamba#153)

ocf: encoder should implement writer interface (hamba#144)

Signed-off-by: Jonas Brunsgaard <[email protected]>

Revert "feat: support recursive types (hamba#139)"

This reverts commit b51e911.

feat: support recursive types (hamba#139)

feat: expose record and field doc (hamba#132)

feat: optimise struct codec (hamba#133)