fix spec

npm_and_yarn/spec/dependabot/npm_and_yarn/update_checker_spec.rb

@@ -55,6 +55,10 @@
   end
   let(:registry_listing_url) { "#{registry_base}/#{escaped_dependency_name}" }
   let(:registry_base) { "https://registry.npmjs.org" }
+
+  # Variable to control the npm fallback version feature flag
+  let(:npm_fallback_version_above_v6_enabled) { false }
+
   # Variable to control the enabling feature flag for the corepack fix
   let(:enable_corepack_for_npm_and_yarn) { true }
 
@@ -65,6 +69,8 @@
       .to_return(status: 200)
     allow(Dependabot::Experiments).to receive(:enabled?)
       .with(:enable_corepack_for_npm_and_yarn).and_return(enable_corepack_for_npm_and_yarn)
+    allow(Dependabot::Experiments).to receive(:enabled?)
+      .with(:npm_fallback_version_above_v6).and_return(npm_fallback_version_above_v6_enabled)
   end
 
   after do