Update dependabot.yml to remove 3.1.x checks

.github/dependabot.yml

@@ -1,10 +1,5 @@
 version: 2
 updates:
-  - package-ecosystem: "github-actions"
-    directory: "/"
-    target-branch: "3.1.x" # oldest OSS supported branch
-    schedule:
-      interval: "weekly"
   - package-ecosystem: "github-actions"
     directory: "/"
     target-branch: "4.0.x" # oldest OSS supported branch
@@ -15,17 +10,6 @@ updates:
     target-branch: "main"
     schedule:
       interval: "weekly"
-  - package-ecosystem: maven
-    directory: /
-    schedule:
-      interval: daily
-    target-branch: 3.1.x
-    ignore:
-      # only upgrade patch versions for maintenance branch
-      - dependency-name: "*"
-        update-types:
-          - version-update:semver-major
-          - version-update:semver-minor
   - package-ecosystem: maven
     directory: /
     schedule: