CI: Release start (#788)

* Initial version

* Fix branch pattern

* Fix template

* Update .github/ISSUE_TEMPLATE/release.md

Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>

* Update .github/ISSUE_TEMPLATE/release.md

Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>

* Rebase master and fmt

* Swap out Polkadot JS section for integration tests + remove tags

* remove tags

Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>

cumulus/.github/workflows/release-99_bot-announce.yml

@@ -0,0 +1,23 @@
+name: Pushes release notes to a Matrix room
+on:
+  release:
+    types:
+      - published
+
+jobs:
+  ping_matrix:
+    runs-on: ubuntu-latest
+    steps:
+      - name: send message
+        uses: s3krit/matrix-message-action@v0.0.3
+        with:
+          room_id: ${{ secrets.MATRIX_ROOM_ID }}
+          access_token: ${{ secrets.MATRIX_ACCESS_TOKEN }}
+          message: |
+            A (pre)release has been ${{github.event.action}} in **${{github.event.repository.full_name}}:**<br/>
+            Release version: [${{github.event.release.tag_name}}](${{github.event.release.html_url}})
+
+            -----
+
+            ${{github.event.release.body}}
+          server: "matrix.parity.io"