Run mixed-version tests with 3.13 weekly

Author: mkuratczyk

.github/workflows/test-mixed.yaml

@@ -0,0 +1,25 @@
+name: Test Mixed with 3.13
+on:
+  schedule:
+    # at 2:20am on Sundays
+    - cron: 20 2 * * 0
+  workflow_dispatch:
+jobs:
+  test-mixed-clusters:
+    name: Test mixed clusters
+    strategy:
+      fail-fast: false
+      matrix:
+        erlang_version:
+        - '26'
+        elixir_version:
+        - '1.18'
+        metadata_store:
+          - mnesia
+    uses: ./.github/workflows/test-make-tests.yaml
+    with:
+      erlang_version: ${{ matrix.erlang_version }}
+      elixir_version: ${{ matrix.elixir_version }}
+      previous_version: 'tags/v3.13.7'
+      metadata_store: ${{ matrix.metadata_store }}
+      mixed_clusters: true