fix(transport): Fix retry strategy not working after req.Body read on the first try.

[antgilles]

Issue :

Retry strategy is not working correctly on go client probably since version 4.
After an http error 502 on the first try. The next attempts to reach fallback host are failing with this error :

> ALGOLIA DEBUG: do not know how to display &url.Error{Op:"Post", URL:"https://CTIR4UHXJG-2.algolianet.com/1/indexes/test_index/query?hitsPerPage=1", Err:http.nothingWrittenError{error:(*errors.errorString)(0xc000628ad0)}}
took 8.799µs
cannot perform request:
	error=Post "https://CTIR4UHXJG-2.algolianet.com/1/indexes/test_index/query?hitsPerPage=1": http: ContentLength=13 with Body length 0
	method=POST

FIX :

Use req.GetBody function to recreate the request body when needed for retry strategy

[github-actions]

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