Revert "Add dummy extension with an empty diff"

This reverts commit 772c336.

Author: asgerf

ruby/ql/lib/emptydiff.model.yml

@@ -16,5 +16,4 @@ dependencies:
 dataExtensions:
   - codeql/ruby/frameworks/**/model.yml
   - codeql/ruby/frameworks/**/*.model.yml
-  - '*.model.yml'
 warnOnImplicitThis: true