chore: update to python 3

Dockerfile

@@ -1,4 +1,4 @@
-FROM python:2.7.16
+FROM python:3
 
 LABEL maintainer="Joakim Olsson <joakim@unbound.se>"
 LABEL description="Base image for running Robot Framework test suites in Docker. \
@@ -18,12 +18,12 @@ RUN apt-get update && \
         apt-get -y install jq && \
         rm -r /var/lib/apt/lists/* && \
         pip install \
-        urllib3==1.22 \
+        urllib3 \
         psycopg2-binary \
         PyMySQL \
         robotframework \
         robotframework-appiumlibrary \
-        robotframework-databaselibrary==1.1.1 \
+        robotframework-databaselibrary \
         robotframework-httplibrary \
         robotframework-rabbitmq \
         robotframework-selenium2library