Handle additional properties

[athith-g]

Currently, py-tes throws errors when encountering properties that are not in the TES specs. For example, when using py-tes v0.4.2 with funnel v0.11.0, the presence of ignore_error in the response body produces the following traceback (from proTES #176):

However, since additionalProperties is not false in the TES specs, any additional spec provided should be handled without throwing an error.

[uniqueg]

Thanks for reporting @athith-g. I agree that py-tes should handle additional props gracefully - the current implementation is not spec-compliant.