Ensure "pytest-remotedata>=0.3.1" to resolve error

Errors:

    >       remote_data = item.get_marker('remote_data')
    E       AttributeError: 'Function' object has no attribute 'get_marker'

REF:

    - https://stackoverflow.com/questions/54254337/pytest-attributeerror-function-object-has-no-attribute-get-marker
    - pytest-dev/pytest#4608
    - pytest-dev/pytest-cov#252

	modified:   environment.yml

Author: tallamjr

environment.yml

@@ -23,6 +23,7 @@ dependencies:
     - emcee>=2.1.0
     - numpy=1.18.4
     - numpydoc>=0.6.0
+    - pytest-remotedata>=0.3.1
     - pywavelets>=0.4.0
     - sncosmo==1.7.1
     - nose>=1.3.7