Fix exception when validation against empty list

[TheSuperiorStanislav]

When making a request to a list action and getting the empty list, the validator fails because it mistakenly passes an empty dict instead of the original response.

[codecov]

Codecov Report

Merging #265 (25a064f) into master (758f49b) will not change coverage.
The diff coverage is 100.0%.

@@           Coverage Diff           @@
##           master     #265   +/-   ##
=======================================
  Coverage   100.0%   100.0%           
=======================================
  Files           9        9           
  Lines         492      492           
  Branches       97       97           
=======================================
  Hits          492      492           

Impacted Files	Coverage Δ
openapi_tester/loaders.py	100.0% <100.0%> (ø)
openapi_tester/schema_tester.py	100.0% <100.0%> (ø)

[TheSuperiorStanislav]

Dunno why checks for linting falling, because it doesn't complain on my changes

[sondrelg]

Looks good to me. I'll see if we can update the linters in master; maybe that will fix it.

[sondrelg]

Thanks @TheSuperiorStanislav!