upgrade hackney to 3.x

[acrogenesis]

All 87 tests pass (1 skipped, same as before).
Bumped version to 2.7.0

  mix.exs: "~> 1.16" → "~> 3.2"

lib/ex_aws/request/hackney.ex:

• Removed :with_body from opts — it's deprecated and ignored in 3.x (body is now
  always returned in the response tuple)
• Removed the unreachable {:ok, status, headers} 3-tuple clause — in 3.x all
  responses return {:ok, status, headers, body}

dialyzer:

Total errors: 0, Skipped: 0, Unnecessary Skips: 0
done in 0m2.21s
done (passed successfully)

[acrogenesis]

these changes were made by mix format