do not test exact wording in xml exception

[jreidinger]

Problem

Ruby 3.4 use nicer formatting in inspect. And Yast2.rpm tests failing. with something like

expected Yast::XMLSerializationError with message matching /represent nil, part of .*"c"=>nil/, got #<Yast::XMLSerializationError: Cannot represent nil, part of {"a" => "b", "b" => "c", "c" => nil, "d" => "e", "e" => "f"}>

Solution

Do not test exact wording in yast exception and test just that exception is properly raised with proper type.

[coveralls]

coverage: 41.889%. remained the same
when pulling 0b30d36 on ruby34
into 717d99f on master.

[github-actions]

✅ Autosubmission job #12580438554 successfully finished
✅ Created submit request #1234526