fix: downgrade rand_core to 0.6 for argon2 compatibility

rand_core 0.9.x changed OsRng API (no longer implements RngCore directly)
and is incompatible with argon2 0.5.x which depends on rand_core 0.6.x.
This caused compilation failures in CI.

Cargo.lock

@@ -2766,9 +2766,9 @@ dependencies = [
 
 [[package]]
 name = "tempfile"
-version = "3.24.0"
+version = "3.25.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "655da9c7eb6305c55742045d5a8d2037996d61d8de95806335c7c86ce0f82e9c"
+checksum = "0136791f7c95b1f6dd99f9cc786b91bb81c3800b639b3478e561ddb7be95e5f1"
 dependencies = [
  "fastrand",
  "getrandom 0.3.4",

Cargo.toml

@@ -32,7 +32,7 @@ sqlx = { version = "0.8.6", features = ["postgres", "runtime-tokio", "tls-rustls
 anyhow = "1.0.101"
 jsonwebtoken = { version = "10.1.0", features = ["rust_crypto"] }
 argon2 = "0.5.3"
-rand_core = { version = "0.9.5", features = ["std"] }
+rand_core = { version = "0.6", features = ["std", "getrandom"] }
 hyper = { version = "1.8.1", features = ["full"] }
 quick-xml = "0.39.0"
 dotenv = "0.15.0"