Unpin Redis 4.3.0 from all images

[stronk7]

Once https://tracker.moodle.org/browse/MDL-66139 is integrated, we can safely unpin current redis 4.3.0 from all branches and allow them to use the newer redis 5.0.x (or whatever php freely picks)

[stronk7]

All the needed PRs have been created (7 in total). To be merged once https://tracker.moodle.org/browse/MDL-66139 is available upstream.

[stronk7]

Have merged all them... once the docker builds end... I'll close this.

[stronk7]

Done, all affected tags have been rebuilt, next week CI will be running them (will perform some docker prune once current jobs are done)