fix: demo-tt/pom.xml to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JAVA-ORGAPACHETOMCATEMBED-5953331
- https://snyk.io/vuln/SNYK-JAVA-ORGAPACHETOMCATEMBED-5959653
- https://snyk.io/vuln/SNYK-JAVA-ORGAPACHETOMCATEMBED-5959654
- https://snyk.io/vuln/SNYK-JAVA-ORGAPACHETOMCATEMBED-5959972

demo-tt/pom.xml

@@ -141,7 +141,7 @@
         <dependency>
             <groupId>org.apache.tomcat.embed</groupId>
             <artifactId>tomcat-embed-core</artifactId>
-            <version>9.0.80</version>
+            <version>9.0.81</version>
             <scope>provided</scope>
         </dependency>
     </dependencies>