Delete combined.yaml

As described in KTibow/ha-blueprint, ha-blueprint is being retired and we should thereby switch over to hassfest and hacs validation.

.github/workflows/combined.yaml

@@ -1,26 +0,0 @@
-name: "Validation And Formatting"
-on:
-  push:
-  pull_request:
-  schedule:
-    - cron: '0 0 * * *'
-jobs:
-  ci:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-        name: Download repo
-        with:
-          fetch-depth: 0
-      - uses: actions/setup-python@v2
-        name: Setup Python
-      - uses: actions/cache@v2
-        name: Cache
-        with:
-          path: |
-            ~/.cache/pip
-          key: custom-component-ci
-      - uses: KTibow/ha-blueprint@stable
-        name: CI
-        with:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}