ci: #17 update maven.yml actions to v4

The PR build workflow (maven.yml) was also using actions/setup-java@v1
with the 'distribution' parameter, but v1 doesn't support that parameter.
Update to v4 for consistency with maven-release.yml.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: tim-brown

.github/workflows/maven-release.yml

@@ -25,10 +25,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - name: Set up JDK 17
+      - name: Set up JDK 21
         uses: actions/setup-java@v4
         with:
-          java-version: 17
+          java-version: 21
           distribution: 'temurin'
       - shell: bash
         env:

.github/workflows/maven.yml

@@ -29,11 +29,11 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
-    - name: Set up JDK 17
-      uses: actions/setup-java@v1
+    - uses: actions/checkout@v4
+    - name: Set up JDK 21
+      uses: actions/setup-java@v4
       with:
-        java-version: 17
+        java-version: 21
         distribution: 'temurin'
     - name: Build with Maven
       run: mvn clean compile test --file pom.xml