[IATI] strip trailing space on schema path in spreadsheets

[stevieflow]

I noticed a file that had the schema path

"transaction/0/sector/@code " - had an extra space in the spreadsheet cell

This led to this fail (the second one applies here)

Whilst it doesn't solve the problem in the data, would it be feasible for CoVE to strip any leading / trailing space on the xpath?

cc/ @IsabelBirds