Remove build-time field to avoid changing all pages on each build

.circleci/config.yml

@@ -11,7 +11,9 @@ commands:
         default: "21,22,23,24,30,31,32,33,34,35,40,41,42,43,44,latest"
     steps:
       - checkout
-      - run: pip install --user tox
+      # NOTE: update tox to tox<5 when https://github.com/tox-dev/tox/issues/2850
+      # is fixed.
+      - run: pip install --user 'tox<4'
       - run: tox -e "<<parameters.version>>-sphinx{<<parameters.sphinx-version>>}"
 
 jobs:

readthedocs_ext/readthedocs.py

@@ -7,11 +7,9 @@
 import os
 import re
 import types
-from datetime import datetime
 from packaging.version import Version
 
 import sphinx
-from sphinx import package_dir
 from sphinx.util.console import bold
 
 
@@ -159,7 +157,6 @@ def rtd_render(self, template, render_context):
                 'api_host': ctx.get('api_host', ''),
                 'commit': ctx.get('commit', ''),
                 'ad_free': ctx.get('ad_free', ''),
-                'build_date': datetime.utcnow().strftime('%Y-%m-%dT%H:%M:%SZ'),
                 'global_analytics_code': ctx.get('global_analytics_code'),
                 'user_analytics_code': ctx.get('user_analytics_code'),
                 'subprojects': dict(ctx.get('subprojects', [])),