Require signed dependency packages

Author: AArnott

src/nuget.config

@@ -2,10 +2,24 @@
 <configuration>
   <config>
     <add key="repositorypath" value="packages" />
+    <add key="signatureValidationMode" value="require" />
   </config>
   <packageSources>
     <clear />
-    <add key="api.nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" />
-    <add key="Consumption" value="https://pkgs.dev.azure.com/andrewarnott/OSS/_packaging/Consumption/nuget/v3/index.json" protocolVersion="3" />
+    <add key="api.nuget.org" value="https://api.nuget.org/v3/index.json" />
+    <add key="Consumption" value="https://pkgs.dev.azure.com/andrewarnott/OSS/_packaging/Consumption/nuget/v3/index.json" />
   </packageSources>
+  <trustedSigners>
+    <repository name="nuget" serviceIndex="https://api.nuget.org/v3/index.json">
+      <owners>Microsoft;aarnott;xunit;kzu;castleproject;patrickb8man;jamesnk;ethomson;AndreyAkinshin;MarcoRossignoli;cake-build;ericnewton76;0xd4d;manuel.roemer</owners>
+      <certificate fingerprint="0e5f38f57dc1bcc806d8494f4f90fbcedd988b46760709cbeec6f4219aa6157d" hashAlgorithm="SHA256" allowUntrustedRoot="false" />
+    </repository>
+    <author name="Nerdbank">
+      <certificate fingerprint="1f891e64936d15de5fae22d910cd39f3e9860213c92f20cf9638a245b1249d2b" hashAlgorithm="SHA256" allowUntrustedRoot="false" />
+    </author>
+    <author name="Microsoft">
+      <certificate fingerprint="aa12da22a49bce7d5c1ae64cc1f3d892f150da76140f210abd2cbffca2c18a27" hashAlgorithm="SHA256" allowUntrustedRoot="false" />
+      <certificate fingerprint="3f9001ea83c560d712c24cf213c3d312cb3bff51ee89435d3430bd06b5d0eece" hashAlgorithm="SHA256" allowUntrustedRoot="false" />
+    </author>
+  </trustedSigners>
 </configuration>