Upgrade to paramtools 0.18.3 version

[martinholmer]

New version of ParamTools works with new marshmallow 3.22 version.

[martinholmer]

@jdebacker, Can you provide any insight about why T-C PR #2800 is generating this error?

Perhaps this GitHub error is related to the following error I get on my local computer:

Tax-Calculator% conda env upgrade
usage: conda-env [-h] {create,export,list,remove,update,config} ...
conda-env: error: argument {create,export,list,remove,update,config}: invalid choice: 'upgrade' (choose from 'create', 'export', 'list', 'remove', 'update', 'config')
Tax-Calculator% conda env update 
Collecting package metadata (repodata.json): done
Solving environment: failed

ResolvePackageNotFound: 
  - paramtools[version='>=0.18.3']

[jdebacker]

@martinholmer I think this replicates PR #2799, correct?