fix unused trust-dns imports #1608

Job	Run time
Docs	1m 30s
Check Style	4s
Android	23s
MSRV	4m 49s
linux / nightly	1m 17s
linux / stable	42s
unstable features	23s
WASM	1m 1s
linux / beta	3m 26s
macOS / stable	4m 3s
windows / stable-x86_64-msvc	6m 36s
windows / stable-i686-msvc	4m 25s
windows / stable-x86_64-gnu	6m 25s
windows / stable-i686-gnu	7m 22s
feat.: default-tls disabled	3m 5s
feat.: rustls-tls	1m 5s
feat.: rustls-tls-manual-roots	57s
feat.: native-tls	57s
feat.: default-tls and rustls-tls	1m 1s
feat.: cookies	1m 8s
feat.: blocking	1m 13s
feat.: gzip	58s
feat.: brotli	1m 3s
feat.: deflate	1m 8s
feat.: json	1m 2s
feat.: multipart	58s
feat.: stream	1m 4s
feat.: socks/default-tls	1m 9s
feat.: socks/rustls-tls	1m 10s
feat.: trust-dns	1m 11s
CI is green	1s
	1h 1m 36s

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