Merge pull request #31 from Chilipp/py35-fix

Remove f-strings

Author: Chilipp

.travis.yml

@@ -6,6 +6,7 @@ python:
   - "3.8"
   - "3.7"
   - "3.6"
+  - "3.5"
 env:
   - SPHINX_VERSION=""
   - SPHINX_VERSION=3.2.*

autodocsumm/__init__.py

@@ -527,8 +527,8 @@ def run(self):
         except (KeyError, ValueError, TypeError) as exc:
             # an option is either unknown or has a wrong type
             logger.error(
-                f'An option to {self.name} is either unknown or has an invalid '
-                f'value: {exc}',
+                'An option to %s is either unknown or has an invalid '
+                'value: %s', self.name, exc,
                 location=(self.env.docname, lineno))
             return []