Dependabot config is invalid

[targos]

See https://github.com/nodejs/node/pull/59320/checks?check_run_id=54873748809

Dependabot encountered the following error when parsing your .github/dependabot.yml:

The property '#/updates/0/open-pull-requests-limit' of type string did not match the following type: integer
The property '#/updates/1/open-pull-requests-limit' of type string did not match the following type: integer
The property '#/updates/2/open-pull-requests-limit' of type string did not match the following type: integer
The property '#/updates/3/open-pull-requests-limit' of type string did not match the following type: integer

Please update the config file to conform with Dependabot's specification.
For more info on the config file format, see the config file documentation

[rxiddhi]

Hey @targos! This PR fixes an issue where Dependabot couldn’t parse .github/dependabot.yml because open-pull-requests-limit was set as a GitHub Actions expression. Dependabot needs a literal integer, so the config was failing validation.

I’ve replaced the expression with a numeric value, and the YAML now parses properly.

This should unblock Dependabot runs. Let me know if anything else is needed!