Update workflows and Docker image references

- Modify `.gitattributes` to use "ours" merge strategy for specific workflow and Docker Compose files.
- Update `nightly.yml` to allow manual triggering and set permissions for content writing.
- Change Docker image reference for `minecraft-lce-dedicated-server` service to a new source.

.github/workflows/nightly.yml

@@ -1,15 +1,7 @@
 name: Nightly Releases
 
 on:
-  workflow_dispatch: 
-  push:
-    branches:
-    - 'main'
-    - 'feature/dedicated-server'
-    paths-ignore:
-      - '.gitignore'
-      - '*.md'
-      - '.github/*.md'
+  workflow_dispatch:
 
 permissions:
   contents: write