fix: path for XSLTLint execution in workflow

Author: greystate

.github/workflows/self-test.yml

@@ -7,5 +7,5 @@ jobs:
 
     steps:
       - name: Running XSLTLint on itself
-        run: xsltproc --xinclude XSLTLint.xslt XSLTLint.xslt
+        run: xsltproc --xinclude ../XSLTLint.xslt ../XSLTLint.xslt