Pin old version of Markupsafe

New version of Markup safe breaks with old Jinja version. To work around it, an older version of Markupsafe needs to be manually added (manubot/rootstock#459). I added version 2.0.1 to the environment YAML (pallets/markupsafe#284).

Author: Daniela C. Soto

build/environment.yml

@@ -7,6 +7,7 @@ dependencies:
   - cffi=1.12.3
   - ghp-import=0.5.5
   - jinja2=2.11.2
+  - markupsafe=2.0.1
   - jsonschema=3.2.0
   - pandoc=2.9.2
   - panflute=1.12.5