Don't run linters on irrelevant files

[lorawoodford]

Oh, and an additional comment (that doesn't change my approval) but if we're sticking with the xslt directory location for this and future files, we can file a quick ticket to skip running the python linter and unit tests when a commit only includes changes to the xslt dir. There's no need to run those checks (or get failures) when the only modifications are to xslt files. The small task could be a chance for @crugas to get some actions experimentation in.

Originally posted by @lorawoodford in #78 (comment)