close body_io after callback

[mwlang]

Webmock is closing the body_io stream before it can be accessed in the after_live_request callback. This PR moves that close action to after the callback call and places in ensure block so an exception raised in the callback doesn't block the close

Example use-case: https://github.com/mwlang/binance/blob/master/spec/support/vcr.cr#L53-L79