Bump dubbo in /sofa-boot-project/sofaboot-dependencies (#928)

Bumps [dubbo](https://github.com/apache/incubator-dubbo) from 2.6.7 to 2.6.9.
- [Release notes](https://github.com/apache/incubator-dubbo/releases)
- [Changelog](https://github.com/apache/dubbo/blob/3.0/CHANGES.md)
- [Commits](apache/dubbo@dubbo-2.6.7...dubbo-2.6.9)

---
updated-dependencies:
- dependency-name: com.alibaba:dubbo
  dependency-type: direct:production
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

sofa-boot-project/sofaboot-dependencies/pom.xml

@@ -46,7 +46,7 @@
 
         <resteasy.version>3.6.3.Final</resteasy.version>
         <curator.version>4.0.1</curator.version>
-        <dubbo.version>2.6.7</dubbo.version>
+        <dubbo.version>2.6.9</dubbo.version>
         <zkclient.version>0.11</zkclient.version>
         <nacos.version>1.0.0</nacos.version>
         <swagger.version>2.0.0</swagger.version>