ci(dependabot): open dependabot PRs only for major versions

Currently, dependabot PRs primarily only update the patch and minor
versions of the crates package for checking typos. Restrict this to
only major version updates.

.github/dependabot.yml

@@ -3,5 +3,9 @@ version: 2
 updates:
   - package-ecosystem: "github-actions"
     directory: "/" # Location of package manifests
+    ignore:
+      update-types:
+        - "version-update:semver-minor"
+        - "version-update:semver-patch"
     schedule:
       interval: "weekly"