librhash: modernize + bump 1.4.2

[madebr]

Specify library name and version: librhash/all/

for conan-io/hooks#320

---

• I've read the guidelines for contributing.
• I've followed the PEP8 style guides for Python code in the recipes.
• I've used the latest Conan client version.
• I've tried at least one configuration locally with the
  conan-center hook activated.

[conan-center-bot]

All green in build 14 (fc3545b7a30ff73cf28ecf1d0e4b68e0b30f5eb9):

• librhash/1.4.2@:
  All packages built successfully! (All logs)

• librhash/1.3.9@:
  All packages built successfully! (All logs)