Set the parameters field/column default type to type dict

[ukanga]

Closes https://github.com/XLSForm/pyxform/issues/605

Why is this the best possible solution? Were any other approaches considered?

Minimal code change, works. See additional context and information on the issue https://github.com/XLSForm/pyxform/issues/605.

What are the regression risks?

None

Does this change require updates to documentation? If so, please file an issue here and include the link below.

No

Before submitting this PR, please make sure you have:

• [x] included test cases for core behaviour and edge cases in tests
• [x] run nosetests and verified all tests pass
• [x] run black pyxform tests to format code
• [x] verified that any code or assets from external sources are properly credited in comments

[lindsay-stevens]

Hi @ukanga OK with the fix in general but I propose #607

[lognaturel]

Thanks! I do like the additions in #607 and hopefully you will as well.

[ukanga]

Closing in favour of #607