fix: add rustls-platform-verifier flag for importing ConfigBuilderExt #478

Job	Run time
Clippy	49s
Check for documentation errors	21s
features	1m 38s
Build+test (stable, ubuntu-latest)	2m 47s
Build+test (beta, ubuntu-latest)	3m 1s
msrv	1m 49s
Build+test (nightly, ubuntu-latest)	2m 45s
Format	4s
Check semver compatibility	49s
Build+test (macos-latest, stable)	2m 40s
Build+test (windows-latest, stable)	8m 53s
	25m 36s

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