v0.12.0: update to rustls 0.22, address breaking changes #1321

Job	Run time
Valgrind	50s
ensure-header-updated	1m 6s
Build+test (clang, stable, ubuntu-20.04)	48s
Format	15s
Check for documentation errors	19s
Build+test (clang, beta, ubuntu-20.04)	52s
Windows	2m 13s
Windows CMake, Debug configuration	1m 53s
Build+test (clang, nightly, ubuntu-20.04)	42s
Clang Tidy	13s
Build+test (clang, 1.61.0, ubuntu-20.04)	4m 42s
Build+test (gcc, stable, ubuntu-20.04)	36s
Clippy	23s
Build+test (gcc, beta, ubuntu-20.04)	38s
Clippy nightly (optional)	29s
Build+test (gcc, nightly, ubuntu-20.04)	36s
Check minimum versions	48s
Build+test (gcc, 1.61.0, ubuntu-20.04)	5m 24s
Miri	53s
Build+test (macos-latest, clang, stable)	1m 23s
Windows CMake, Release configuration	1m 52s
	26m 55s

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