fix: Sync Workflow Lives in Chronon (#743)

## Summary

My strategy to use a reuseble workflow doesn't work anymore because a
private workflow isn't accessible from a public repo. Instead of
triggering the sync, this simply runs it from here.

## Checklist
- [ ] Added Unit Tests
- [ ] Covered by existing CI
- [ ] Integration tested
- [ ] Documentation update



<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

- **Chores**
- Removed the previous canary release workflow, including automated
build, test, and artifact deployment steps for AWS and GCP.
- Introduced a new workflow to automate synchronization of code from the
chronon repository into the platform repository via subtree pull and
push operations.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: chewy-zlai

.github/workflows/push_to_platform.yaml

@@ -0,0 +1,56 @@
+name: Push to Platform
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  subtree-pull:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout platform repo
+        uses: actions/checkout@v4
+        with:
+          repository: "zipline-ai/platform"
+          ssh-key: ${{ secrets.PLATFORM_REPO_DEPLOY_KEY }}
+          fetch-depth: 0  # Required for subtree operations
+          ref: main       # Ensure we're on the main branch
+
+      - name: Set up Git config
+        run: |
+          git config user.name "GitHub Actions"
+          git config user.email "[email protected]"
+
+      - name: Set up SSH key for Chronon access and pull subtree
+        env:
+          SSH_PRIVATE_KEY: ${{ secrets.CHRONON_REPO_DEPLOY_KEY }}
+        run: |
+          mkdir -p ~/.ssh
+          echo "$SSH_PRIVATE_KEY" > ~/.ssh/id_rsa
+          chmod 600 ~/.ssh/id_rsa
+          
+          # Add GitHub's SSH key to known_hosts
+          ssh-keyscan github.com >> ~/.ssh/known_hosts
+          
+          # Set up SSH agent
+          eval "$(ssh-agent -s)"
+          ssh-add ~/.ssh/id_rsa
+          
+          # Create basic SSH config
+          cat > ~/.ssh/config << EOF
+          Host github.com
+            User git
+            IdentityFile ~/.ssh/id_rsa
+            StrictHostKeyChecking no
+          EOF
+          
+          # Add the SSH remote
+          git remote add chronon [email protected]:zipline-ai/chronon.git || true
+          
+          git fetch chronon main
+          git subtree pull --prefix=chronon chronon main --message="chore: update chronon subtree"
+
+      - name: Push changes to platform
+        run: git push origin main