fix: allow merging loader name with loader object

[just-jeb]

PR Checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

Loaders merge might fail because one of Angular loaders is defined as a string and not as an object. More info here and here.

What is the new behavior?

Builder update to a newer version of webpack-merge in which this issue is fixed.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

[autoapproval]

Approved 👍