[CI] Install dependabot and update julia-actions/setup-julia (#60)

[skip ci]

Author: giordano

.github/dependabot.yml

@@ -0,0 +1,7 @@
+# https://docs.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/" # Location of package manifests
+    schedule:
+      interval: "weekly"

.github/workflows/ci.yml

@@ -45,7 +45,7 @@ jobs:
         run: |
           git config --global --add safe.directory "${PWD}"
           git status
-      - uses: julia-actions/setup-julia@v1
+      - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.julia_version }}
       - uses: julia-actions/cache@v1