Bug 1881540 - Enable Dependabot for pyproject.toml too

.github/dependabot.yml

@@ -1,5 +1,13 @@
 version: 2
 updates:
+- package-ecosystem: pip
+  directory: "/"
+  schedule:
+    interval: daily
+  open-pull-requests-limit: 99
+  labels:
+  - dependencies
+  - python
 - package-ecosystem: pip
   directory: "/requirements"
   schedule: