Bump System.IO.Pipelines from 4.5.0 to 4.5.1 in /WebApi (#45)

Bumps [System.IO.Pipelines](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)

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

WebApi/packages.config

@@ -32,7 +32,7 @@
   <package id="System.Buffers" version="4.5.0" targetFramework="net461" />
   <package id="System.Configuration.ConfigurationManager" version="4.5.0" targetFramework="net461" />
   <package id="System.Diagnostics.PerformanceCounter" version="4.5.0" targetFramework="net461" />
-  <package id="System.IO.Pipelines" version="4.5.0" targetFramework="net461" />
+  <package id="System.IO.Pipelines" version="4.5.1" targetFramework="net461" />
   <package id="System.Memory" version="4.5.0" targetFramework="net461" />
   <package id="System.Numerics.Vectors" version="4.4.0" targetFramework="net461" />
   <package id="System.Runtime.Caching" version="4.5.0" targetFramework="net461" />