Sync matrix

[Narkunan]

Fix issue #923

[github-actions]

This PR touches files which potentially affect the outcome of the tests of an exercise. This will cause all students' solutions to affected exercises to be re-tested.

If this PR does not affect the result of the test (or, for example, adds an edge case that is not worth rerunning all tests for), please add the following to the merge-commit message which will stops student's tests from re-running. Please copy-paste to avoid typos.

[no important files changed]

For more information, refer to the documentation. If you are unsure whether to add the message or not, please ping @exercism/maintainers-admin in a comment. Thank you!

[Narkunan]

@mk-mxp Sorry I faced some sync with previous PR so created a new one. Please provide your feedback. I am happy to work on them

[mk-mxp]

@Narkunan To avoid that kind of trouble, you can follow these steps:

• Before starting a PR, create a branch on your fork and commit to it (you did this already, I think)
• Open the PR from the new branch to main here (you also did this, I believe)
• After a PR was merged, first delete your branch using the button below the merged PR's discussion - this deletes the branch from your GitHub fork
• Then sync your fork to this repository again - this updates main of your fork
• Then sync your local git repository using git checkout main and git pull -p - this updates main and deletes the remote branch configuration
• At last, delete the local branch using git branch -D $YOUR_BRANCH

This workflow keeps your local copy as close as possible to the Exercism main branch and tidies it up. I'm now reading through your changes...

[mk-mxp]

Thank you for investing the time to sync this! Please take a look at the test data, too, before you submit the next exercise. The differences are everywhere...

[mk-mxp]

A bit of misunderstanding, I see. The comment block in the students code (Matrix.php) is wanted, the other two (example.php and MatrixTest.php) shall go.

[mk-mxp]

Thanks a lot for the contribution! Looking forward to the next exercise.