fix: updated extendDictionary to be truly deep and fixed tests

[PetrKukla]

Before submitting the PR, please make sure you do the following

• It's really useful if your PR references an issue where it is discussed ahead of time.
• Prefix your PR title with feat:, fix:, chore:, or docs:.
• This message body should clearly illustrate what problems it solves.
• Ideally, include a test that fails without this PR but passes with it.

Tests

• Run the tests with pnpm test and lint the project with pnpm lint

Bug

• The extendDictionary was not really doing deep extend. It just replaced the top-level properties.

Solution

• I added true as a first argument to the call of extend function from just-extend package to do the desired deep extend.
• Also I updated the tests, because they were not catching this issue.