feat(droneci): support for multiline string image dependency

[ns-ggeorgiev]

Fix for issue #15576

Changes

The droneci manager is modified to properly detect when image is specified on multiple lines. For example:

image: "amd64/node:10.0.0\
        @sha256:36adc17e9cceab32179d3314da9cb9c737ffb11f0de4e688f407ad6d9ca32201"

Context

Documentation (please check one with an [x])

• I have updated the documentation, or
• [ x ] No documentation update is required

How I've tested my work (please tick one)

I have verified these changes via:

• Code inspection only, or
• [ x ] Newly added/modified unit tests, or
• No unit tests but ran on a real repository, or
• [ x ] Both unit tests + ran on a real repository:
  https://github.com/ggeorgiev/renovate-test/pull/2/files
  https://github.com/ggeorgiev/renovate-test/pull/3/files

[rarkins]

• please reduce debug logging to trace
• can you demonstrate the .drone.yml full updates on a public repo with the new code? (both regular style as well as the newly supported formats)

[ns-ggeorgiev]

@rarkins how I can do that. Even if I create the repo, how I can run the code from the fork on it?

[rarkins]

https://github.com/renovatebot/renovate/blob/main/docs/development/local-development.md#run-against-a-real-repo

[rarkins]

Needs demo in real repo, both old and new cases to verify all works/updates

[ns-ggeorgiev]

real repo demo links in the description

[ns-ggeorgiev]

@rarkins any reason to sit on this?

[renovate-release]

🎉 This PR is included in version 32.58.0 🎉

The release is available on:

• GitHub release
• 32.58.0

Your semantic-release bot 📦🚀