Options to specify strategy

[taughz]

Adds new arguments the pytest.yaml reusable workflow, to make it easier to specify a strategy. To generate the strategy, a small utility genstrat.py has been added. By default, this utility will output a file identical to the old strategy.json (which has been deleted). It is still possible to use matrix-filter, if a user prefers to use that.

Resolves: #37

[taughz]

Can someone please look at this PR?

[taughz]

So I know there was a response to #37, but I wonder if you might still consider merging this PR? It doesn't add too much code, it is backwards compatible. This is just my opinion, but I think it's easier to understand than the jq filter. I am using this fork for my own Colcon extension, which I will be making public soon, hopefully.

[taughz]

Here's my Colcon extension, and the workflow using the updated action: https://github.com/taughz/colcon-package-of/blob/98cc23b70348a2b171cf6f48415dacb934047032/.github/workflows/ci.yaml#L16

jobs:
  pytest:
    uses: taughz/colcon-ci/.github/workflows/pytest.yaml@main
    with:
      strategy-os: |
        macos-latest
        ubuntu-22.04
      strategy-python: |
        3.10
        3.11
        3.12
      strategy-include-py36: false
      strategy-include-stdeb: false