Add nuget.config for package source configuration

Author: BigBadJock

nuget.config

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+  <packageSources>
+    <clear />
+    <add key="nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" />
+    <add key="bigbadjock-github" value="https://nuget.pkg.github.com/bigbadjock/index.json" />
+  </packageSources>
+  <add key="signatureValidationMode" value="accept" />
+  <packageSourceCredentials>
+    <bigbadjock-github>
+      <add key="Username" value="%GITHUB_PACKAGES_USER%" />
+      <add key="ClearTextPassword" value="%GITHUB_PACKAGES_PAT%" />
+    </bigbadjock-github>
+  </packageSourceCredentials>
+</configuration>