ci: install pypandoc in ci and as tox dependency

Author: mmlb

.drone.yml

@@ -18,5 +18,5 @@ pipeline:
     image: python:${PYTHON_VERSION}
     commands:
       - apt update -y && apt install -y pandoc
-      - pip install tox
+      - pip install pypandoc tox
       - tox

.travis.yml

@@ -11,5 +11,5 @@ python:
   - "3.6"
 sudo: false
 
-install: pip install tox
+install: pip install pypandoc tox
 script: tox

tox.ini

@@ -4,6 +4,7 @@ skip_missing_interpreters=True
 
 [testenv]
 deps =
+     pypandoc
      pytest
      pytest-cov
      requests_mock