CI: add missing uv installation step

Author: ctrueden

.github/workflows/build.yml

@@ -46,6 +46,11 @@ jobs:
         distribution: 'zulu'
         cache: 'maven'
 
+    - name: Set up uv
+      run: |
+        python -m pip install --upgrade pip
+        python -m pip install uv
+
     - name: Run tests
       run: |
         bin/test.sh