Create release workflow

.github/workflows/release.yml

@@ -0,0 +1,49 @@
+#  For more information about TARDIS pipelines, please refer to:
+#
+#    https://tardis-sn.github.io/tardis/development/continuous_integration.html
+
+name: release
+
+on:
+  pull_request:
+    types: [closed]
+
+jobs:
+  create:
+    if: startsWith(github.head_ref, 'pre-release-20') && github.event.pull_request.merged == true
+
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+
+      - name: Setup Python
+        uses: actions/setup-python@v3
+        with:
+          python-version: '3.x'
+
+      - name: Install setuptools_scm
+        run: pip install setuptools_scm
+
+      - name: Show current version
+        run: python .ci-helpers/get_current_version.py
+
+      - name: Get next version
+        run:  |
+          python .ci-helpers/get_next_version.py
+          echo "NEW_TAG=$(python .ci-helpers/get_next_version.py)" >> $GITHUB_ENV
+
+      - name: Create new release
+        uses: softprops/action-gh-release@v1
+        with:
+          token: ${{ secrets.BOT_TOKEN }}
+          name: TARDIS v${{ env.NEW_TAG}}
+          tag_name: release-${{ env.NEW_TAG }}
+          prerelease: false
+          body: |
+            This release has been made automatically through the TARDIS continuous delivery pipeline.
+
+            For a complete list of changes see [CHANGELOG.md](https://github.com/tardis-sn/tardis/blob/master/CHANGELOG.md).
+          files: *.lock
+          fail_on_unmatched_files: false