update compiler veresion to 21

Author: zhongkechen

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -53,7 +53,6 @@ body:
       label: Java Version
       description: What version of Java are you using?
       options:
-        - "17"
         - "21"
         - "25"
         - Other (specify in additional context)

examples/src/test/java/software/amazon/lambda/durable/examples/CloudBasedIntegrationTest.java

@@ -502,7 +502,6 @@ void testManyAsyncStepsExample(int steps, long maxExecutionTime, long maxReplayT
     }
 
     @ParameterizedTest
-    // OOM if it creates 1000 child contexts
     @CsvSource({"100, 1500, 10", "500, 3000, 20", "1000, 4500, 30", "2000, 10000, 50"})
     void testManyAsyncChildContextExample(int steps, long maxExecutionTime, long maxReplayTime) {
         long minimalExecutionTimeMs = Long.MAX_VALUE;

pom.xml

@@ -46,8 +46,8 @@
     </modules>
 
     <properties>
-        <maven.compiler.source>25</maven.compiler.source>
-        <maven.compiler.target>25</maven.compiler.target>
+        <maven.compiler.source>21</maven.compiler.source>
+        <maven.compiler.target>21</maven.compiler.target>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <aws.sdk.version>2.42.8</aws.sdk.version>
         <jackson.version>2.21.1</jackson.version>