build(deps): bump commons-net in /examples/async-thumbnails

Bumps commons-net from 3.8.0 to 3.9.0.

---
updated-dependencies:
- dependency-name: commons-net:commons-net
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

examples/async-thumbnails/pom.xml

@@ -50,7 +50,7 @@
         <dependency>
             <groupId>commons-net</groupId>
             <artifactId>commons-net</artifactId>
-            <version>3.8.0</version>
+            <version>3.9.0</version>
         </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>