[MRG] Add dependabot (#325)

* Add dependabot

* add line at the end

---------

Co-authored-by: Antoine Collas <contact@antoinecollas.fr>

Author: lionelkusch

.github/dependabot.yml

@@ -0,0 +1,20 @@
+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    groups:
+      actions:
+        patterns:
+          - "*"
+  - package-ecosystem: pip
+    directory: "/"
+    allow:
+      - dependency-type: all
+    schedule:
+      interval: "weekly"
+    groups:
+      python-packages:
+        patterns:
+          - "*"