fix(host): bound ed25519-dalek below v3

Host test utilities use rand_core 0.6 through rand_chacha 0.3. Fresh lockfiles otherwise select ed25519-dalek 3 and fail the CryptoRng bound.

Fixes #1705

Author: kalepail

soroban-env-host/Cargo.toml

@@ -24,7 +24,7 @@ sha2 = "0.10.8"
 hex-literal = "0.4.1"
 hmac = "0.12.1"
 # NB: We'll need to pin this again after switching the Core to the new env version.
-ed25519-dalek = {version = ">=2.0.0", features = ["rand_core"] }
+ed25519-dalek = {version = ">=2.0.0, <3.0.0", features = ["rand_core"] }
 # NB: this must match the same rand version used by ed25519-dalek above
 rand = "0.8.5"
 # NB: this must match the same rand_chacha version used by ed25519-dalek above