Merge pull request #37 from Chaste/upgrade-github-actions

Upgrade github actions

Merge pull request #36 from martinjrobins/split-voltage-for-apd90-cal…

…c-variant

feat: run 3 paces to calculate apd90

Merge pull request #31 from Chaste/issue30_always_fetchcontent

Release to go with Chaste release 2021.1

Adjust tests a teeny bit for new steady state running

Update copyright

Update submodule

Update README.md