use dependabot groups for nuget

Author: arturcic

.github/dependabot.yml

@@ -25,6 +25,9 @@ updates:
       patterns:
       - "Microsoft.Extensions.*"
       - "System.*"    
+    serilog:
+      patterns:
+      - "Serilog.*"
   directory: "/new-cli"
   schedule:
     interval: daily
@@ -40,7 +43,7 @@ updates:
       patterns:
       - "Microsoft.Extensions.*"
       - "System.*"
-  directory: "/"
+  directory: "/src"
   schedule:
     interval: daily
   open-pull-requests-limit: 10