Revert "config: bump Saxon-HE to 9.8.0-7"

This reverts commit 76373c3239084cce5b39394d18a2fba2f1d1241f.
diff --git a/pom.xml b/pom.xml
index 185aa59..6be363d 100644
--- a/pom.xml
+++ b/pom.xml
@@ -218,7 +218,7 @@
     <maven.pmd.plugin.version>3.8</maven.pmd.plugin.version>
     <pmd.version>5.8.1</pmd.version>
     <maven.jacoco.plugin.version>0.7.9</maven.jacoco.plugin.version>
-    <saxon.version>9.8.0-7</saxon.version>
+    <saxon.version>9.8.0-6</saxon.version>
     <maven.checkstyle.plugin.version>2.17</maven.checkstyle.plugin.version>
     <maven.sevntu.checkstyle.plugin.version>1.25.0</maven.sevntu.checkstyle.plugin.version>
     <maven.sevntu-checkstyle-check.checkstyle.version>8.5</maven.sevntu-checkstyle-check.checkstyle.version>