Update _attributes.adoc

Author: ammbra

documentation/modules/advanced/pages/_attributes.adoc

@@ -3,7 +3,7 @@
 :advanced-module-github-repo-uri: https://github.com/redhat-developer-demos/knative-tutorial-advanced
 :advanced-github-repo-uri: https://github.com/redhat-developer-demos/knative-tutorial-advanced
 :advanced-github-re17po: {advanced-module-github-repo-uri}/blob/{branch}
-:kamel-version: 1.3.1
+:kamel-version: 1.8.0
 :experimental:
 :maven-version: 3.6.3+
 :strimzi-version: 0.26.1