Unskip test

Ran rspec locally 45 times and it never failed.

hex/spec/dependabot/hex/file_parser_spec.rb

@@ -376,7 +376,7 @@
         )
       end
 
-      it "parses the dependencies correctly", skip: "Hex upgrade work is in progress" do
+      it "parses the dependencies correctly" do
         expect(dependencies.length).to eq(3)
         expect(dependencies).to include(
           Dependabot::Dependency.new(