fix: Hackney leaks {ssl_closed, _} back to oc_reporter

[bipthelin]

Tracked here: benoitc/hackney#464
this became apparent when using oc_google_reporter which uses Hackney

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[bipthelin]

@googlebot I signed it!

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[bipthelin]

@googlebot I fixed it.

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[kbip]

@googlebot I consent.

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[bipthelin]

This PR does not fully fix the problem. Closing for now

[astutecat]

@bipthelin We've got this happening frequently enough on a system that I'm working on that it's crashing the VM. Did you come across a workaround to this at all?

[bipthelin]

@bipthelin We've got this happening frequently enough on a system that I'm working on that it's crashing the VM. Did you come across a workaround to this at all?

This commit fixed it for us: opencensus-beam/oc_google_reporter@bb578a5

It seems that if you don't close hackney either explicitly with hackney:close(Ref) or implicitly by reading the body the pool will eventually get exhausted.

[astutecat]

thanks for this!