fix: enable feature flags to which deltalake-core build tokio with en…

…able_io()

`cargo build` just in core was broken previously. When building at the
root of the project this did not fail because some combination of
feature flags for tokio were being used during that `cargo` run

crates/core/Cargo.toml

@@ -66,8 +66,10 @@ futures = { workspace = true }
 num_cpus = { workspace = true }
 tokio = { workspace = true, features = [
     "macros",
+    "process",
     "rt",
     "rt-multi-thread",
+    "signal",
     "sync",
     "fs",
     "parking_lot",