Fix missed mentions of 1.29

[tcharding]

Oops,

$ cargo search bitcoin-hashes
bitcoin_hashes = "0.11.0"    # Hash functions used by rust-bitcoin which support rustc 1.29.0

• Patch one fixes the crate description
• Patch two clears a couple of mentions in the test script

We could almost do a point release if we (cough apoelstra ) were keen, I'll raise the 'bump version' PR if anyone agrees to make him do the work :)

[apoelstra]

Lol, I don't think we need to do a release just to fix the wording on crates.io.