Use renovate to update git submodule branch and commit

Question

I am using renovate to update a git submodule, this configuration works fine.

{
    "$schema": "https://docs.renovatebot.com/renovate-schema.json",
    "git-submodules": {
        "enabled": true,
        "versioning": "git",
        "fileMatch": [
            "(^|/)\\.gitmodules$"
        ]
    }
}

I introduced branches to my .gitmodules file and I am trying to figure out how to make renovate update the branch to the latest (as well as the commit).

[submodule "my_submodule"]
    path = path/to/submodule
    url = submodule_url
    branch = release/2.0

I tried to change "versioning": "git" to "versioning": "semver" and "versioning": "regex:^release/(?<major>\\d+)(\\.(?<minor>\\d+))".