build(deps): bump fop from 2.7 to 2.8

Bumps fop from 2.7 to 2.8.

---
updated-dependencies:
- dependency-name: org.apache.xmlgraphics:fop
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

extensions/modules/xslfo/pom.xml

@@ -80,7 +80,7 @@
         <dependency>
             <groupId>org.apache.xmlgraphics</groupId>
             <artifactId>fop</artifactId>
-            <version>2.7</version>
+            <version>2.8</version>
             <exclusions>
                 <!--
                     fop-core depends on javax.servlet:servlet-api:jar:2.2