Add hassfest action (#22)

* Add hassfest action

* Fix manifest issue

.github/workflows/hassfest.yaml

@@ -0,0 +1,14 @@
+name: Validate with hassfest
+
+on:
+  push:
+  pull_request:
+  schedule:
+    - cron:  '0 0 * * *'
+
+jobs:
+  validate:
+    runs-on: "ubuntu-latest"
+    steps:
+        - uses: "actions/checkout@v2"
+        - uses: home-assistant/actions/hassfest@master

custom_components/blueprint/manifest.json

@@ -10,6 +10,5 @@
   "requirements": [
     "sampleclient",
     "integrationhelper"
-  ],
+  ]
-  "homeassistant": "0.96.0"
 }