Bump org.apache.sling.servlets.post from 2.1.2 to 2.3.8

Bumps org.apache.sling.servlets.post from 2.1.2 to 2.3.8.

---
updated-dependencies:
- dependency-name: org.apache.sling:org.apache.sling.servlets.post
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
diff --git a/pom.xml b/pom.xml
index 7cc0c0b..ecd2820 100644
--- a/pom.xml
+++ b/pom.xml
@@ -132,7 +132,7 @@
         <dependency>
             <groupId>org.apache.sling</groupId>
             <artifactId>org.apache.sling.servlets.post</artifactId>
-            <version>2.1.2</version>
+            <version>2.3.8</version>
             <scope>provided</scope>
         </dependency>
         <dependency>