test(schematron): fix typo in test example file

[galtm]

I came across a typo in an example file that supports a test.

[AirQuick]

Thanks for spotting it.

If the typo didn't include 's, codespell could have caught it.

C:\>echo excpect's|codespell -

C:\>echo excpect|codespell -
1: excpect
        excpect ==> expect