Specify helm-diff version in Docker build (#974)

Author: AndrewKostka

.github/workflows/docker.build.yml

@@ -28,6 +28,8 @@ jobs:
         with:
           helmfile-version: 'v0.162.0'
           helm-version: 'v3.12.2'
+          helm-plugins: >
+            https://github.com/databus23/helm-diff@v3.12.5
       - name: Cache Docker layers
         uses: actions/cache@v4
         with: