Only update patch versions on main

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

Author: ryanjbaxter

.github/dependabot.yml

@@ -37,11 +37,12 @@ updates:
     schedule:
       interval: daily
     target-branch: main
-#    ignore:
-#      # only upgrade by minor or patch
-#      - dependency-name: "*"
-#        update-types:
-#          - version-update:semver-major
+    ignore:
+      # only upgrade patch versions for maintenance branch
+      - dependency-name: "*"
+        update-types:
+          - version-update:semver-major
+          - version-update:semver-minor
   - package-ecosystem: npm
     target-branch: docs-build
     directory: /