Document the min/max Items/Length fields if the attribute uses the length validator

[dhruvCW]

Grape 2.1.0 Introduced the length validator . We can now use the length validator to specify the min/maxItems (for array types) and min/maxLength (for String types) for the attributes that use the validator in the generated swagger document.

Fixed test that was broken with rack 3 and restricted rack < 3 for grape < 2

[dhruvCW]

Test failures seem unrelated to this PR 🤔 fixed the broken tests.

There grape < 2.0 seems to require rack < 3.0 and there was a test that didn't set it's body that was breaking with rack 3.

[LeFnord]

thanks @dhruvCW … yeah it makes sense