Upgrade to GitHub-native Dependabot (#176)

* Upgrade to GitHub-native Dependabot

* Update dependabot.yml

* Update dependabot.yml

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>
Co-authored-by: Stephen Colebourne <stephen@opengamma.com>

Author: dependabot-preview[bot]

.github/dependabot.yml

@@ -0,0 +1,47 @@
+version: 2
+
+updates:
+- package-ecosystem: maven
+  directory: "/"
+  schedule:
+    interval: weekly
+    time: "02:30"
+  open-pull-requests-limit: 20
+  reviewers:
+  - jodastephen
+  assignees:
+  - jodastephen
+  ignore:
+  - dependency-name: com.beust:jcommander
+    versions:
+    - "< 1.73.1, >= 1.73.0.a"
+  - dependency-name: com.beust:jcommander
+    versions:
+    - "< 1.74.1, >= 1.74.0.a"
+  - dependency-name: com.beust:jcommander
+    versions:
+    - ">= 1.75.a, < 1.76"
+  - dependency-name: com.beust:jcommander
+    versions:
+    - ">= 1.80.a, < 1.81"
+  - dependency-name: com.beust:jcommander
+    versions:
+    - ">= 1.81.a, < 1.82"
+  - dependency-name: com.opengamma:corporate-parent
+    versions:
+    - "> 2.7.3, < 2.8"
+  - dependency-name: com.squareup.okhttp3:mockwebserver
+    versions:
+    - ">= 4.a, < 5"
+  - dependency-name: com.squareup.okhttp3:okhttp
+    versions:
+    - ">= 4.a, < 5"
+  - dependency-name: com.squareup.okio:okio
+    versions:
+    - "< 2.3, >= 2.2.a"
+  - dependency-name: com.squareup.okio:okio
+    versions:
+    - ">= 2.a, < 3"
+  - dependency-name: org.testng:testng
+    versions:
+    - "< 6.14.4, >= 6.14.3.a"