Enable TLS integration test

[crepererum]

We already have a TLS integration test here

rskafka/tests/client.rs

Lines 73 to 75 in 3af1939

	// Disabled as currently no TLS integration tests
	#[ignore]
	#[tokio::test]

but it is disabled because our CI doesn't set up any form of TLS. Would be nice if we could get this to work. Ideally the test would be gated by some environment variable like TLS_ENDPOINT so that developers can still run a rather simple cargo test locally.

[toondaey]

Would it be possible to switch ci to github actions?

[crepererum]

@toondaey what would be the advantage of switching?