minisign: update to 0.10.

- Minisign can be compiled with Zig instead of cmake+make+a C toolchain
- Minimal VERIFY_ONLY versions can be built again
- Prehashing is now enabled by default, regardless of the input size. Support
  for non-prehashed signatures will eventually be removed
- Legacy signatures can be rejected with the addition of the -H flag

(fcambus)