zeroize: Allow versions newer than 1.3 for aes-gcm-siv (solana-labs…

…#33618)

`aes-gcm-siv` v0.10.3 has a constraints on maximum `zeroize` version,
set to be 1.3 or below.

At the same time, `cargo` does not want to construct a dependency graph
with duplicate instances of a crate, when the first non-zero version of
those instances are the same.  That is, it refuses to build a workspace
with both 1.3 and 1.4 versions of `zeroize`.

`zeroize` is actually backward compatible, and `aes-gcm-siv` restriction
is overly pessimistic.  This package lifted this restriction in a newer
versions, but we still depend on older versions and can not immediately
update.

In order to be able to use a version of `zeroize` newer than 1.3 we need
to remove a similar restriction from `curve25519-dalek` as well.

Cargo.toml

@@ -397,6 +397,7 @@ wasm-bindgen = "0.2"
 winapi = "0.3.8"
 winreg = "0.10"
 x509-parser = "0.14.0"
+# See "zeroize versioning issues" below if you are updating this version.
 zeroize = { version = "1.3", default-features = false }
 zstd = "0.11.2"