Support wagtail 2.16

[fabienheureux]

Support wagtail 2.16

Wagtail 2.16 is now out, this PR adds support for this new version.

Note : I added wagtail 2.15 and 2.16 to github actions as we currently only test with wagtail 2.14.
Is there a reason these versions were not tested in the CI ?

---

• Testing
  • CI passes
  • These changes do not reduce test coverage
• Documentation.
  • This PR adds or updates documentation

[fabienheureux]

Note for later : we might want to define the matrix inside a json file and load it using fromJson in the github action, or use something like https://tomasvotruba.com/blog/2020/11/16/how-to-make-dynamic-matrix-in-github-actions/ as it would prevent the duplicated block in the workflow file

[fabienheureux]

Question : is it worth testing against all wagtail versions here ? Or is it safe to assume it is already tested against them in the previous job ?

[nickmoreton]

Thanks @fabienheureux

Note : I added wagtail 2.15 and 2.16 to github actions as we currently only test with wagtail 2.14.
Is there a reason these versions were not tested in the CI ?

Not that I can think of. It's likely we just haven't caught up yet, pretty sure 2.15 was the current release when we started the project so not sure why we didn't have that in there.

[nickmoreton]

@fabienheureux Thanks for the PR. LGTM. I will merge this in and get a new release in place today.

Note for later : we might want to define the matrix inside a json file and load it using fromJson in the github action, or use something like https://tomasvotruba.com/blog/2020/11/16/how-to-make-dynamic-matrix-in-github-actions/ as it would prevent the duplicated block in the workflow file

Will add your note to a new issue and we can continue the discussion there. 👍

[fabienheureux]

Thanks for the merge, regarding my note I already created an issue to track this #153