chore: remove duplicate nightly (#3154)

.github/workflows/docker-image-nightly.yml

@@ -1,30 +0,0 @@
-name: Docker Image CI (nightly)
-
-on:
-  schedule:
-    - cron: '35 10 * * *' # 10:35am UTC, 2:35am PST, 5:35am EST
-  release:
-    types: [published]
-  workflow_dispatch:
-
-jobs:
-
-  build:
-
-    runs-on: ubuntu-latest
-
-    steps:
-    - name: Login to Docker Hub
-      uses: docker/login-action@v3
-      with:
-        username: ${{ secrets.DOCKERHUB_USERNAME }}
-        password: ${{ secrets.DOCKERHUB_TOKEN }}
-
-    - uses: actions/checkout@v3
-    - name: Build and push the Docker image (letta)
-      run: |
-        docker build . \
-          --file Dockerfile \
-          --tag letta/letta:nightly \
-          --build-arg LETTA_VERSION="nightly-$(date +%Y%m%d)-$(git rev-parse --short HEAD)"
-        docker push letta/letta:nightly