CVEhound 1.6.1

Fixed `.grep` rules silently reporting a clean kernel on macOS: the rules are PCRE, but check_cve() called plain `grep`, and BSD grep's missing `-P` support (exit 2) was read the same as "no match" (exit 1) — five CVEs cleared without a byte examined. cvehound now probes for `-P` support before running .grep rules, trying `grep` then `ggrep`.

`cvehound[spatch]` now resolves on Apple Silicon: cvehound-spatch publishes a macosx_11_0_arm64 wheel as of 1.3.2.post3, so the extra's marker no longer excludes darwin/arm64 (Intel Macs still have no wheel and stay excluded).

Full Changelog: 1.6.0...1.6.1