gemspec.json does not work

[mpkorstanje]

👓 What did you see?

The workaround (renovatebot/renovate#10616) we use to support .gemspec files stopped working when we upgraded from regexManagers to customManagers in a74b839.

The current configuration should include:

"customManagers": [
    {
      "customType" :"regex",

But doing so will break renovate as explained in renovatebot/renovate#28090.

🔬 Next steps

Await the resolution of renovatebot/renovate#28090 and then add customType to the gemspec.json file.