[#2159] Remove JDK 23 testing

Author: DavideD

.github/workflows/build.yml

@@ -191,7 +191,6 @@ jobs:
           # and it's useful to test that.
           - { name: "20", java_version_numeric: 20, jvm_args: '--enable-preview' }
           - { name: "21", java_version_numeric: 21, jvm_args: '--enable-preview' }
-          - { name: "23", java_version_numeric: 23, from: 'jdk.java.net', jvm_args: '--enable-preview' }
           - { name: "24-ea", java_version_numeric: 24, from: 'jdk.java.net', jvm_args: '--enable-preview' }
           - { name: "25-ea", java_version_numeric: 25, from: 'jdk.java.net', jvm_args: '--enable-preview' }
     steps: