Use yaml.safe_load instead of yaml.load

[Kami]

This Tweet made me grep our code for yaml.load - https://twitter.com/anthonypjshaw/status/1014054816987803648

I was almost positive we already use yaml.safe_load everywhere, but it looks like a couple of yaml.load occurrences managed to creep into the tests.

It's not a big deal to do that in the tests. It's mostly problematic in places where we take user input, but it's still a good practice to use yaml.safe_load if there is no special reason / need to use yaml.load.

Thanks @tonybaloney

[arm4b]

@tonybaloney's original #4222 was first 😛

[Kami]

@armab ah, lol, I didn't even see that one. Will close this one as a duplicate of #4222.

Or maybe Github just doesn't correctly handle nano second precision and I was actually the first one

[arm4b]

looks like it's 6 mins in diff between 2 PRs :)

[Kami]

@armab No way - must be that we were routed to two different backend servers with local clocks out of sync

[arm4b]

Haha 😄 , that's a good one 👍