Bump System.Text.Encodings.Web in /sample/SkyApm.Sample.AspNet (#412)

Author: dependabot[bot]

sample/SkyApm.Sample.AspNet/packages.config

@@ -35,7 +35,7 @@
   <package id="System.Memory" version="4.5.3" targetFramework="net461" />
   <package id="System.Numerics.Vectors" version="4.5.0" targetFramework="net461" />
   <package id="System.Runtime.CompilerServices.Unsafe" version="4.7.0" targetFramework="net461" />
-  <package id="System.Text.Encodings.Web" version="4.7.0" targetFramework="net461" />
+  <package id="System.Text.Encodings.Web" version="4.7.2" targetFramework="net461" />
   <package id="System.Text.Json" version="4.7.0" targetFramework="net461" />
   <package id="System.Threading.Tasks.Extensions" version="4.5.3" targetFramework="net461" />
   <package id="System.ValueTuple" version="4.5.0" targetFramework="net461" />