feat: add zeroize feature to wipe blake3 internal key material on drop

Cargo.lock

@@ -19,6 +19,9 @@ name = "arrayvec"
 version = "0.7.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7c02d123df017efcdfbd739ef81735b36c5ba83ec3c59c80a9d7ecc718f92e50"
+dependencies = [
+ "zeroize",
+]
 
 [[package]]
 name = "async-trait"
@@ -49,6 +52,7 @@ dependencies = [
  "cfg-if",
  "constant_time_eq",
  "cpufeatures",
+ "zeroize",
 ]
 
 [[package]]
@@ -482,6 +486,12 @@ dependencies = [
  "windows-link",
 ]
 
+[[package]]
+name = "zeroize"
+version = "1.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b97154e67e32c85465826e8bcc1c59429aaaf107c1e4a9e53c8d8ccd5eff88d0"
+
 [[package]]
 name = "zmij"
 version = "1.0.21"