Update ring to 0.9.4.
Update ring to 0.9.4.

ford-prefect/rusoto,SecurityInsanity/rusoto,DualSpark/rust-aws,rusoto/rusoto,rusoto/rusoto,mattico/rusoto,DualSpark/rust-aws,ford-prefect/rusoto,rusoto/rusoto,DualSpark/rusoto,mattico/rusoto,DualSpark/rusoto,DualSpark/rust-aws,mthjones/rusoto,SecurityInsanity/rusoto,DualSpark/rusoto,mthjones/rusoto,mattico/rusoto