Bump fop from 2.5 to 2.6

Bumps fop from 2.5 to 2.6.

Signed-off-by: dependabot[bot] <support@github.com>
diff --git a/doxia-modules/doxia-module-fo/pom.xml b/doxia-modules/doxia-module-fo/pom.xml
index 1791f6b..7d65eb2 100644
--- a/doxia-modules/doxia-module-fo/pom.xml
+++ b/doxia-modules/doxia-module-fo/pom.xml
@@ -85,7 +85,7 @@
     <dependency>
       <groupId>org.apache.xmlgraphics</groupId>
       <artifactId>fop</artifactId>
-      <version>2.5</version>
+      <version>2.6</version>
       <exclusions>
         <!-- exclude JAI - missing on Maven Central -->
         <exclusion>