Add Java version file to workflows

[mateuszkwiecinski]

No description provided.

[Copilot]

Pull request overview

This PR centralizes the Java version used in GitHub Actions by introducing a repository-level .java-version file and updating workflows to read the JDK version from that file instead of hard-coding it in each workflow.

Changes:

• Add a root .java-version file set to Java 25.
• Update the publish workflow to use java-version-file: .java-version.
• Update the dependency diff workflow to use java-version-file: .java-version (which also changes its effective Java version from 23 to 25).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
.java-version	Adds a single source of truth for the Java version (25).
.github/workflows/publish.yaml	Switches setup-java to read the Java version from .java-version.
.github/workflows/dependencies.yml	Switches setup-java to read the Java version from .java-version (implicitly changing the job’s JDK from 23 to 25).

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[github-actions]

Jar size:

Jar size change: +0.0B (3.4MiB -> 3.4MiB)

Diffuse output:

OLD: diffuse-source-file
NEW: diffuse-unspecified-r8.jar

       │        compressed        │       uncompressed       
       ├─────────┬─────────┬──────┼─────────┬─────────┬──────
 JAR   │ old     │ new     │ diff │ old     │ new     │ diff 
───────┼─────────┼─────────┼──────┼─────────┼─────────┼──────
 class │ 1.8 MiB │ 1.8 MiB │  0 B │ 3.2 MiB │ 3.2 MiB │  0 B 
 other │ 1.6 MiB │ 1.6 MiB │  0 B │   5 MiB │   5 MiB │  0 B 
───────┼─────────┼─────────┼──────┼─────────┼─────────┼──────
 total │ 3.4 MiB │ 3.4 MiB │  0 B │ 8.1 MiB │ 8.1 MiB │  0 B 

 CLASSES │ old  │ new  │ diff      
─────────┼──────┼──────┼───────────
 classes │ 1353 │ 1353 │ 0 (+0 -0) 
 methods │ 7820 │ 7820 │ 0 (+0 -0) 
  fields │ 3327 │ 3327 │ 0 (+0 -0)