Fix vulnerability in NuGet dependencies

[StefH]

No description provided.

[codecov]

Codecov Report

Merging #508 into master will increase coverage by 0.04%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master     #508      +/-   ##
==========================================
+ Coverage   75.97%   76.01%   +0.04%     
==========================================
  Files         136      135       -1     
  Lines        5252     5249       -3     
  Branches      517      517              
==========================================
  Hits         3990     3990              
+ Misses       1108     1105       -3     
  Partials      154      154              

Impacted Files	Coverage Δ
...eMock.Net/Settings/WireMockServerSettingsParser.cs	0.00% <0.00%> (ø)
src/WireMock.Net/Server/WireMockServer.Admin.cs	56.61% <100.00%> (ø)
...rc/WireMock.Net/Settings/ProxyAndRecordSettings.cs	77.77% <100.00%> (ø)

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[StefH]

#507