minor #175 Add configuration for Dependabot (phansys)

This PR was merged into the 3.x branch.

Discussion
----------

|Q            |A  |
|---          |---|
|Branch       |3.x|
|Bug fix?     |no |
|New feature? |no |
|BC breaks?   |no |
|Deprecations?|no |
|Tests pass?  |yes|
|Fixed tickets|   |
|License      |MIT|
|Doc PR       |   |

Commits
-------

ea249a7 Add configuration for Dependabot

.github/dependabot.yml

@@ -0,0 +1,12 @@
+version: 2
+
+updates:
+  - package-ecosystem: composer
+    directory: '/'
+    schedule:
+      interval: daily
+      time: '02:00'
+    open-pull-requests-limit: 10
+    target-branch: master
+    allow:
+      - dependency-type: all