Remove 4.2.x branch from dependabot

Removed deprecated GitHub Actions and Maven configurations for the 4.2.x target branch.

Signed-off-by: Ryan Baxter <ryan.baxter@broadcom.com>

.github/dependabot.yml

@@ -16,11 +16,6 @@ updates:
     target-branch: "4.3.x"
     schedule:
       interval: "weekly"
-  - package-ecosystem: "github-actions"
-    directory: "/"
-    target-branch: "4.2.x"
-    schedule:
-      interval: "weekly"
   - package-ecosystem: maven
     directory: /
     schedule:
@@ -51,21 +46,6 @@ updates:
         update-types:
           - version-update:semver-major
           - version-update:semver-minor
-  - package-ecosystem: maven
-    directory: /
-    schedule:
-      interval: daily
-    target-branch: 4.2.x
-    ignore:
-      # IDE specific dependency
-      - dependency-name: "org.eclipse.m2e:lifecycle-mapping"
-      # JRuby updates are causing docs generation to fail
-      - dependency-name: "org.jruby:jruby-complete"
-      # only upgrade by minor or patch
-      - dependency-name: "*"
-        update-types:
-          - version-update:semver-major
-          - version-update:semver-minor
   - package-ecosystem: npm
     target-branch: docs-build
     directory: /
@@ -81,8 +61,3 @@ updates:
     directory: /docs
     schedule:
       interval: weekly
-  - package-ecosystem: npm
-    target-branch: 4.2.x
-    directory: /docs
-    schedule:
-      interval: weekly