renovate: Correct parent config reference

[echarrod]

Fixed

• Config name: renovate-config matches the JSON filename present at https://github.com/luno/.github/ (see docs)
• Tested with forks:
  • https://github.com/echarrod/.github
  • https://github.com/echarrod/luno-go
• Started to change the file name in renovate: Rename config file .github#3, but thought this was better since that repo has non-renovate items in, so calling it default.json wouldn't indicate what it's being used for

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud