chore!: Change supported Node from 18 to 20 (#20669)

* chore!: Change supported Node from 18 to 20

Node 20 is the active LTS version for Node.

Node 18 will be end of life soon and new libraries like React 19 support Node 20+

* Fix tests

Author: Artur-

flow-server/src/main/java/com/vaadin/flow/server/frontend/FrontendTools.java

@@ -117,9 +117,9 @@ public class FrontendTools {
     private static final FrontendVersion WHITESPACE_ACCEPTING_NPM_VERSION = new FrontendVersion(
             7, 0);
 
-    private static final int SUPPORTED_NODE_MAJOR_VERSION = 18;
-    private static final int SUPPORTED_NODE_MINOR_VERSION = 12;
-    private static final int SUPPORTED_NPM_MAJOR_VERSION = 8;
+    private static final int SUPPORTED_NODE_MAJOR_VERSION = 20;
+    private static final int SUPPORTED_NODE_MINOR_VERSION = 0;
+    private static final int SUPPORTED_NPM_MAJOR_VERSION = 9;
     private static final int SUPPORTED_NPM_MINOR_VERSION = 6;
 
     static final FrontendVersion SUPPORTED_NODE_VERSION = new FrontendVersion(

flow-server/src/test/java/com/vaadin/flow/server/frontend/FrontendToolsTest.java

@@ -69,7 +69,7 @@
 @Category(SlowTests.class)
 public class FrontendToolsTest {
 
-    private static final String SUPPORTED_NODE_BUT_OLDER_THAN_AUTOINSTALLED = "18.12.0";
+    private static final String SUPPORTED_NODE_BUT_OLDER_THAN_AUTOINSTALLED = "20.0.0";
 
     public static final String DEFAULT_NODE = FrontendUtils.isWindows()
             ? "node\\node.exe"

flow-test-generic/src/main/java/com/vaadin/flow/testutil/FrontendStubs.java

@@ -254,8 +254,8 @@ public String getScript() {
      */
     public static class ToolStubBuilder {
 
-        private static final String DEFAULT_NPM_VERSION = "8.6.0";
-        private static final String DEFAULT_NODE_VERSION = "18.12.0";
+        private static final String DEFAULT_NPM_VERSION = "10.9.0";
+        private static final String DEFAULT_NODE_VERSION = "22.12.0";
 
         private String version;
         private String cacheDir;