sdk 8.0.204 and add nuget CVE audit

[SimonCropp]

This PR is to show how Octostache will fail a CVE audit because it has a transitive reference to vunerable versions of System.Text.RegularExpressions and System.Net.Http

Can you please update to versions with no CVE so as to not force that change on all consumers

C:\Code\Octostache\source\Octostache\Octostache.csproj : error NU1903: Warning As Error: Package 'System.Text.RegularEx
pressions' 4.3.0 has a known high severity vulnerability, https://github.com/advisories/GHSA-cmhx-cq75-c4mj [C:\Code\Oc
tostache\source\Octostache.sln]
  Failed to restore C:\Code\Octostache\source\Octostache\Octostache.csproj (in 22 sec).
C:\Code\Octostache\source\Octostache.Tests\Octostache.Tests.csproj : error NU1903: Warning As Error: Package 'System.Ne
t.Http' 4.3.0 has a known high severity vulnerability, https://github.com/advisories/GHSA-7jgj-8wvc-jh57 [C:\Code\Octos
tache\source\Octostache.sln]
C:\Code\Octostache\source\Octostache.Tests\Octostache.Tests.csproj : error NU1903: Warning As Error: Package 'System.Te
xt.RegularExpressions' 4.3.0 has a known high severity vulnerability, https://github.com/advisories/GHSA-cmhx-cq75-c4mj
 [C:\Code\Octostache\source\Octostache.sln]

[JessThrysoee]