Fix doc builds (#622)

* Update test_env.yaml

* try using main yaml

* use mamba to build env

* Update test_env.yaml

* Update test_env.yaml

lets see if we can still drop parmed here

devtools/conda-envs/test_env.yaml

@@ -13,6 +13,7 @@ dependencies:
   - numba
   - numpy
   - openmm >=7.5.0
+  #- parmed  # Test to see if this fixes the docs
   - pip
   - pymbar <4
   - python
@@ -27,3 +28,8 @@ dependencies:
   - nose-timer
   - pytest
   - pytest-cov
+
+  # docs
+  - numpydoc
+  - sphinxcontrib-bibtex
+

readthedocs.yml

@@ -1,12 +1,14 @@
 conda:
-  file: docs/environment.yml
+  file: devtools/conda-envs/test_env.yaml
 
 # The default for requirements_file is null, but for some reason we get an error with this message if it's not set:
 # "Problem parsing YAML configuration. Invalid "requirements_file": path docs/requirements.txt does not exist"
 requirements_file: null
 
 build:
   image: latest
+  tools:
+    python: mambaforge-4.10
 
 python:
   version: 3.6