[#4169] Update JDKs for workflows

JDK 26 has been moved to Adoptium
JDK 27 went GA (September 2026)
JDK 28-ea is available from jdk.java.net

Author: DavideD

.github/workflows/build.yml

@@ -256,8 +256,9 @@ jobs:
           # and it's useful to test that.
           - { name: "21", java_version_numeric: 21, jvm_args: '--enable-preview' }
           - { name: "25", java_version_numeric: 25, jvm_args: '--enable-preview' }
-          - { name: "26", java_version_numeric: 26, from: 'jdk.java.net', jvm_args: '--enable-preview' }
-          - { name: "27-ea", java_version_numeric: 27, from: 'jdk.java.net', jvm_args: '--enable-preview' }
+          - { name: "26", java_version_numeric: 26, jvm_args: '--enable-preview' }
+          - { name: "27", java_version_numeric: 27, from: 'jdk.java.net', jvm_args: '--enable-preview' }
+          - { name: "28-ea", java_version_numeric: 28, from: 'jdk.java.net', jvm_args: '--enable-preview' }
     steps:
       - name: Checkout ${{ inputs.branch }}
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1