fix: Percy/Percy.csproj to reduce vulnerabilities (#164)

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DOTNET-SYSTEMNETHTTP-60045
- https://snyk.io/vuln/SNYK-DOTNET-SYSTEMNETHTTP-60046
- https://snyk.io/vuln/SNYK-DOTNET-SYSTEMNETHTTP-60047
- https://snyk.io/vuln/SNYK-DOTNET-SYSTEMNETHTTP-60048
- https://snyk.io/vuln/SNYK-DOTNET-SYSTEMNETHTTP-72439
- https://snyk.io/vuln/SNYK-DOTNET-SYSTEMTEXTREGULAREXPRESSIONS-174708

Co-authored-by: snyk-bot <[email protected]>

Author: AgnellusX1

Percy/Percy.csproj

@@ -23,7 +23,7 @@
     <RestorePackagesWithLockFile>true</RestorePackagesWithLockFile>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="Castle.Core" Version="4.3.1"/>
+    <PackageReference Include="Castle.Core" Version="5.0.0"/>
     <PackageReference Include="Microsoft.CSharp" Version="4.7.0"/>
     <PackageReference Include="Newtonsoft.Json" Version="13.0.1"/>
   </ItemGroup>