Pin sha2 version, as the version afterward automatically picked is broken apparently and requires latest rust toolchain

Author: slinkydeveloper

Cargo.toml

@@ -24,6 +24,7 @@ rand = { version = "0.8.5", optional = true }
 regress = "0.10"
 restate-sdk-macros = { version = "0.3.2", path = "macros" }
 restate-sdk-shared-core = "0.1.0"
+sha2 = "=0.11.0-pre.3"
 serde = "1.0"
 serde_json = "1.0"
 thiserror = "1.0.63"