Provide some examples of using matrix-filter

[taughz]

I see you can use jq queries to modify the strategy matrix. I would like to only test Python versions 3.10 and later. But I only know basic jq queries, so I'm not sure how to do this. An example would be very helpful. (Anyway, I am reading the jq documentation right now trying to figure it out.)

[taughz]

I could not figure out how to make jq do what I wanted. (I'm sure it's possible, but I have no interest in learning the jq language just to make trivial modifications.) Instead, I added some more convenient inputs to the workflow in #38. The default behavior is to produce a strategy identical to the current strategy.json, so it is backwards compatible.

[cottsay]

This filter does what you want: jq 'del((.matrix.python[] | select(. == "3.8", . == "3.9")), (.matrix.include[] | select(.python == "3.6")))' strategy.json