Matrix: Fix input string for test case 'can extract column from non-s…

[DagmarTimmreck]

…quare matrix with no corresponding row'

[DagmarTimmreck]

I am really sorry, but in the first PR #1576 there were extra spaces in the test data.

I hope I didn't break anything and apologize for the extra work.

[sshine]

I'm sorry for approving without noticing this. Thank you for putting in the extra work.

Unfortunately, we need to bump the test version once more.

[sshine]

@DagmarTimmreck: Could you push another commit that bumps the version to 1.3.0?

I would do this, but since your pull request is made from master, I cannot push changes to the pull request. If you make feature branches and create pull requests from them, maintainers of the repo you submit the pull request to can push changes, too. But as a security measure, I suppose, I cannot push to your master.

[yawpitch]

Got this fixed in #1578 just in case the bad whitespace was triggering an automated test build that might affect students.