8b9d657667 hashes: Remove unused file (Tobin C. Harding)
Pull request description:
Recently we moved the tests from `impls` to `tests/io.rs` but forgot to delete the original file.
Remove the already unused `impls.rs` file.
ACKs for top commit:
apoelstra:
ACK 8b9d657667 successfully ran local tests
Tree-SHA512: f701825239aff18faa0cd7adf69e1a8830dfb532df9d52c6d545e6352054ae6cb8c625c9fc05b7db374822d3478acf16858bc38ffbecf45575f555eb80f010e1