Upgrading to 3.12.0 (#731)

Author: diemol

Base/Dockerfile

@@ -56,5 +56,5 @@ USER seluser
 #==========
 RUN  sudo mkdir -p /opt/selenium \
   && sudo chown seluser:seluser /opt/selenium \
-  && wget --no-verbose https://selenium-release.storage.googleapis.com/3.11/selenium-server-standalone-3.11.0.jar \
+  && wget --no-verbose https://selenium-release.storage.googleapis.com/3.12/selenium-server-standalone-3.12.0.jar \
     -O /opt/selenium/selenium-server-standalone.jar