add dependabot config, update downgrade compat action

Author: m-fila

.github/dependabot.yml

@@ -0,0 +1,12 @@
+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for all configuration options:
+# https://docs.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+
+version: 2
+updates:
+  # Keep dependencies for GitHub Actions up-to-date
+  - package-ecosystem: 'github-actions'
+    directory: '/'
+    schedule:
+      interval: 'monthly'

.github/workflows/Downgrade.yml

@@ -21,7 +21,7 @@ jobs:
       - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.version }}
-      - uses: cjdoris/julia-downgrade-compat-action@v1
+      - uses: julia-actions/julia-downgrade-compat@v1
         with:
           skip: Pkg,TOML
       - uses: julia-actions/julia-buildpkg@v1