Add bitflags to no_std universe

Summary: Add another crate to `no_std`. This doesn't seem like it's part of the stage0 required deps to be stuffed into `no_std`, but I ran into errors when trying to build stage0 without this

Reviewed By: dtolnay

Differential Revision: D71530327

fbshipit-source-id: f8ec6d4ac0745b9a40aa9880eb7eed44d9a3721d

Author: CookieComputing

below/store/Cargo.toml

@@ -11,7 +11,7 @@ license = "Apache-2.0"
 
 [dependencies]
 anyhow = "1.0.95"
-bitflags = { version = "2.6", features = ["serde"] }
+bitflags = { version = "2.6", features = ["serde", "std"], default-features = false }
 bytes = { version = "1.9.0", features = ["serde"] }
 common = { package = "below-common", version = "0.9.0", path = "../common" }
 humantime = "2.1"