Merge pull request kenkoooo#1163 from kenkoooo/dependabot/cargo/atcoder-problems-backend/futures-util-0.3.21

build(deps): bump futures-util from 0.3.19 to 0.3.21 in /atcoder-problems-backend

Author: kenkoooo

atcoder-problems-backend/Cargo.lock

@@ -31,7 +31,7 @@ reqwest = { version = "0.11", features = ["json"] }
 async-trait = "0.1"
 
 anyhow = "1.0"
-futures-util = "0.3.19"
+futures-util = "0.3.21"
 
 [dev-dependencies]
 httpmock = "0.6.6"