Use environmental variable to set multi version sphinx tag list (#390)

.github/workflows/SphinxBuild_PR.yml

@@ -1,4 +1,4 @@
-name: "docs"
+name: "PR Docs"
 on:
 - pull_request
 
@@ -20,6 +20,7 @@ jobs:
       PYTHONUNBUFFERED: '1'
       PYTHON_VERSION: '3.9'
       MNE_3D_BACKEND: 'pyvistaqt'
+      SMV_TAG_WHITELIST: 'ignore all tags'
     steps:
       - uses: actions/checkout@v2
         with:

doc/conf.py

@@ -27,6 +27,9 @@
 from mne.tests.test_docstring_parameters import error_ignores
 
 
+smv_tag_whitelist = os.getenv('SMV_TAG_WHITELIST', r'^v\d+\.\d+.\d+$')
+
+
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
@@ -57,7 +60,7 @@
 # smv_tag_whitelist = r'^v\d+\.\d+.\d+$'
 # They say to set this to None, but then Sphinx complains about it not being
 # a string, so let's just use a regex that should lead to no tags
-smv_tag_whitelist = 'ignore all tags'
+# smv_tag_whitelist = 'ignore all tags'
 # Mark vX.Y.Z as releases
 smv_released_pattern = r'^.*v.*$'