chore: Enable the default features for futures-util (#4120)

We depend on the `futures_util::steam_select` macro since 9b36a04. This
macro requires the async-await-macros and std feature of futures-util.

These features are the default features so let's just stop disabling the
default features for futures-util.

Signed-off-by: Damir Jelić <poljar@termina.org.uk>
Co-authored-by: Jonas Platte <jplatte@matrix.org>

Author: poljar

Cargo.toml

@@ -36,9 +36,7 @@ eyeball-im = { version = "0.5.0", features = ["tracing"] }
 eyeball-im-util = "0.6.0"
 futures-core = "0.3.28"
 futures-executor = "0.3.21"
-futures-util = { version = "0.3.26", default-features = false, features = [
-    "alloc",
-] }
+futures-util = "0.3.26"
 growable-bloom-filter = "2.1.0"
 http = "1.1.0"
 imbl = "3.0.0"