fix(cms): Downgrade Decap to 3.4.0 and ignore updates

Author: alexwilson

.github/dependabot.yml

@@ -8,10 +8,16 @@ updates:
     ignore:
       - dependency-name: "unist-util-visit"
         versions: ["3.x", "4.x", "5.x"]
-        
-      # React 19 includes some breaking change affecting bundling.
+
+      # React 19 includes some breaking changes affecting bundling.
       - dependency-name: "react"
         versions: ["19.x"]
+
+      # Recent Decap updates have not been stable.
+      - dependency-name: "decap-cms"
+        versions: ["^3.5"]
+      - dependency-name: "decap-cms-app"
+        versions: ["^3.5"]
     reviewers:
       - alexwilson
     versioning-strategy: increase-if-necessary