Test with Python 3.10 and set cancel-in-progress to True

[Saransh-cpp]

Vector supports Python 3.10, but the support is not tested in the CI -

vector/.github/workflows/ci.yml

Lines 31 to 39 in d4ad49e

	fail-fast: false
	matrix:
	python-version:
	- 3.6
	- 3.7
	- 3.8
	- 3.9
	name: Check Python ${{ matrix.python-version }}
	steps:

---

Additionally, the cancel-in-progress field is set to ${{ startsWith(github.ref, 'refs/pull/') }} -

vector/.github/workflows/ci.yml

Lines 11 to 15 in d4ad49e

	concurrency:
	# Skip intermediate builds: always.
	# Cancel intermediate builds: only if it is a pull request build.
	group: ${{ github.workflow }}-${{ github.ref }}
	cancel-in-progress: ${{ startsWith(github.ref, 'refs/pull/') }}

which for some reason returns a string now (unverified bug/incorrect documentation, see - github/docs#19416).

I think it should be okay to set it to true as set here - https://github.com/scikit-hep/cookie/blob/main/%7B%7Bcookiecutter.project_name%7D%7D/.github/workflows/ci.yml#L18-L20.

[henryiii]

Let's add 3.11 too, and do this before release.