fix(docs): update smriprep dependency

Author: oesteban

docs/requirements.txt

@@ -1,12 +1,12 @@
 git+https://github.com/AleksandarPetrov/napoleon.git@0dc3f28a309ad602be5f44a9049785a1026451b3#egg=sphinxcontrib-napoleon
 git+https://github.com/rwblair/sphinxcontrib-versioning.git@39b40b0b84bf872fc398feff05344051bbce0f63#egg=sphinxcontrib-versioning
 nbsphinx
-nipype ~= 1.4.2
+nipype ~= 1.4
 niworkflows ~= 1.1.10
 packaging
 pydot>=1.2.3
 pydotplus
-smriprep ~= 0.5.2
+smriprep >= 0.6.0rc1
 sphinx-argparse
 sphinx>=2.1.2
 sphinx_rtd_theme

setup.cfg

@@ -23,7 +23,7 @@ install_requires =
     dipy >=1.0.0
     indexed_gzip >=0.8.8
     nibabel ~= 3.0
-    nipype ~= 1.4.2
+    nipype ~= 1.4
     niworkflows ~= 1.1.10
     numpy
     pybids >= 0.9.4