Update spring boot to v3.5.6 (#33)

Author: renovate[bot]

pom.xml

@@ -40,7 +40,7 @@
     <properties>
         <maven.compiler.release>17</maven.compiler.release>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <spring-boot.version>3.5.5</spring-boot.version>
+        <spring-boot.version>3.5.6</spring-boot.version>
     </properties>
 
     <dependencies>