NFC-127 Bump Java version to 21 (LTS)

Signed-off-by: Sander Kondratjev <sander.kondratjev@nortal.com>

Author: SanderKondratjevNortal

example/pom.xml

@@ -17,7 +17,7 @@
 	</description>
 
 	<properties>
-		<java.version>17</java.version>
+		<java.version>21</java.version>
 		<maven-surefire-plugin.version>3.5.3</maven-surefire-plugin.version>
 		<webeid.version>4.0.0-SNAPSHOT</webeid.version>
 		<digidoc4j.version>6.0.1</digidoc4j.version>

pom.xml

@@ -11,7 +11,7 @@
     <description>Web eID authentication token validation library for Java</description>
 
     <properties>
-        <java.version>11</java.version>
+        <java.version>21</java.version>
         <jjwt.version>0.12.6</jjwt.version>
         <bouncycastle.version>1.81</bouncycastle.version>
         <jackson.version>2.19.1</jackson.version>