Tag new version and update changelog

Update the changelog with the latest changes to the master branch and tag a new version (current version is v1.0.1). V1.1.0 is the new version as the changes modify the behaviour of existing jobs but not to a major extent.

Proposed changelog:

[1.1.0] - 2020-08-26

Modified

• PEP8: Modified the PEP8 CI template job to be uninterruptible, and to only run for pipelines other than merge request pipelines.
• Tox tests: Modified the Tox tests template to make the documentation job run for pipelines other than merge request pipelines (previously the job was never running due to a bug in the job rules).