Issue #95 - Update Firefox to version 61.0

* Updated the Dockerfile

Author: ppodgorsek

Dockerfile

@@ -15,7 +15,7 @@ ENV SCREEN_WIDTH 1920
 # Dependency versions
 ENV CHROMIUM_VERSION 67.0.*
 ENV FAKER_VERSION 4.2.0
-ENV FIREFOX_VERSION 60.0*
+ENV FIREFOX_VERSION 61.0*
 ENV GECKO_DRIVER_VERSION v0.19.1
 ENV PYTHON_PIP_VERSION 9.0.*
 ENV ROBOT_FRAMEWORK_VERSION 3.0.4