bump gh action java to 17 (was 11). Required for spring boot 3

Author: poblin-orange

pom.xml

@@ -19,7 +19,7 @@
     <description>Spring Boot MongoDB Demo for Cloud Foundry</description>
 
     <properties>
-        <java.version>11</java.version>
+        <java.version>17</java.version>
         <spring-cloud.version>2024.0.0</spring-cloud.version>
 
 	    <docker.image.prefix>ghcr.io/${github.repository}</docker.image.prefix>