Explicitly require dependabot/utils before usage (#7800)

All other ecosystems do it:

```
$ rg ^Dependabot::Utils.register_always_clone -B1
go_modules/lib/dependabot/go_modules.rb
21-require "dependabot/utils"
22:Dependabot::Utils.register_always_clone("go_modules")

pub/lib/dependabot/pub.rb
20-require "dependabot/utils"
21:Dependabot::Utils.register_always_clone("pub")

swift/lib/dependabot/swift.rb
21-require "dependabot/utils"
22:Dependabot::Utils.register_always_clone("swift")

terraform/lib/dependabot/terraform.rb
21-require "dependabot/utils"
22:Dependabot::Utils.register_always_clone("terraform")

npm_and_yarn/lib/dependabot/npm_and_yarn.rb
28-require "dependabot/utils"
29:Dependabot::Utils.register_always_clone("npm_and_yarn")
```

npm_and_yarn/lib/dependabot/npm_and_yarn.rb

@@ -25,4 +25,5 @@
   end
 )
 
+require "dependabot/utils"
 Dependabot::Utils.register_always_clone("npm_and_yarn")