relax regex and zeroize dependencies

These dependencies were bumped without comment or other code change in
ff4beaf.  This reverts that part of
that commit.  "cargo build" and "cargo test" still both pass.

Neither upstream change was necessary to make the package build or
test correctly, from what i can see, and there was no
backward-incompatible API change (the versions are semver-compatible).

There is nothing wrong with raising a dependency when it's needed, but
raising a dependency above the necessary base version makes it harder
to build against older installations.

Cargo.toml

@@ -23,14 +23,14 @@ ml-kem-1024 = []
 
 
 [dependencies]
-zeroize = { version = "1.7.0", default-features = false, features = ["zeroize_derive"] }
+zeroize = { version = "1.6.0", default-features = false, features = ["zeroize_derive"] }
 rand_core = { version = "0.6.4", default-features = false }
 sha3 = { version = "0.10.2", default-features = false }
 
 
 [dev-dependencies]
 rand = "0.8.5"
-regex = "1.10.3"
+regex = "1.10.2"
 hex = "0.4.3"
 rand_chacha = "0.3.1"
 criterion = "0.4.0" # Needed to keep MSRV back at 1.72, newer: "0.5.1"