Bump System.Text.Encodings.Web from 4.7.1 to 4.7.2 in /tools
Bump System.Text.Encodings.Web from 4.7.1 to 4.7.2 in /tools

Bumps [System.Text.Encodings.Web](https://github.com/dotnet/corefx) from 4.7.1 to 4.7.2.
- [Release notes](https://github.com/dotnet/corefx/releases)
- [Commits](https://github.com/dotnet/corefx/commits)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
OmniSharp/omnisharp-roslyn,OmniSharp/omnisharp-roslyn