Issue 211. Test for readonly properties

[shanginn]

Ok, I remember that readonly didn't work for me, but now they are working, so I created a test case for it. In order for it to work we need to add php 8.1 in CI matrix settings.

But php 8.1 will not work with current lower versions.

The questions is - do you want to add php 8.1 support? If no, I can just add the test and it will be waiting for the version upgrade.

There is another question: how should I go about testing this behavior: with marshaller or with payload converter? I created both, but I think that one of them is enough. Or both is good?

What was changed

Added test that covers readonly properties issue

Why?

Because issue is open and I though readonly properties would not work, but surprisingly they are working just fine

Checklist

1. Closes issue 221

2. How was this tested: With unit test

[seregazhuk]

@shanginn have you tried functional tests with your changes? It fails, I think there are errors when running worker under RR. https://github.com/temporalio/sdk-php/runs/7752350196?check_suite_focus=true

[shanginn]

I did check it under my branch, and it went fine

[shanginn]

I rebased (or do you prefer merge?) this branch to the current master. in my fork all the test are good