aws-sdk-cpp: 1.4.40 -> 1.4.50 (#40694)

Semi-automatic update generated by https://github.com/ryantm/nixpkgs-update tools.

This update was made based on information from https://repology.org/metapackage/aws-sdk-cpp/versions.

These checks were done:

- built on NixOS

- 0 of 0 passed binary check by having a zero exit code.
- 0 of 0 passed binary check by having the new version present in output.
- found 1.4.50 with grep in /nix/store/kg9d5flfl989yxfcppyq886g60mfhpzy-aws-sdk-cpp-1.4.50
- directory tree listing: https://gist.github.com/2faf1d98f152431438b23c93bd489e09
- du listing: https://gist.github.com/9df0b904ab22201191bb2261798bb0a3