Ignore tapioca for dependency updates

Ref ruby#4034

rbs 4.0 has been released and now it resolves differently
But we have to wait on steep to release it's new version first
before we can make use of this to properly work

Author: Earlopain

.github/dependabot.yml

@@ -35,3 +35,4 @@ updates:
           - "*"
     ignore:
       - dependency-name: "sorbet"
+      - dependency-name: "tapioca"