Bump System.Text.Encodings.Web (#688)

Bumps [System.Text.Encodings.Web](https://github.com/dotnet/corefx) from 4.5.0 to 4.5.1.
- [Release notes](https://github.com/dotnet/corefx/releases)
- [Commits](https://github.com/dotnet/corefx/commits)

---
updated-dependencies:
- dependency-name: System.Text.Encodings.Web
  dependency-type: direct:production
...

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examples/WireMock.Net.Console.Net472.Classic/packages.config

@@ -74,7 +74,7 @@
   <package id="System.Runtime.CompilerServices.Unsafe" version="5.0.0" targetFramework="net472" />
   <package id="System.Security.Cryptography.Cng" version="4.5.0" targetFramework="net472" />
   <package id="System.Security.Principal.Windows" version="4.5.0" targetFramework="net472" />
-  <package id="System.Text.Encodings.Web" version="4.5.0" targetFramework="net472" />
+  <package id="System.Text.Encodings.Web" version="4.5.1" targetFramework="net472" />
   <package id="System.Threading.Tasks.Extensions" version="4.5.1" targetFramework="net472" />
   <package id="System.ValueTuple" version="4.5.0" targetFramework="net472" />
   <package id="WireMock.Net" version="1.4.2" targetFramework="net472" />