(MAINT) Skip mend checks on community PRs

Copied a conditional from mend_ruby.yml to skip running
mend checks on PRs from forks so that we can avoid false
CI failures from community PRs.

Author: LukasAud

.github/workflows/tooling_mend_ruby.yml

@@ -28,6 +28,7 @@ env:
 
 jobs:
   mend:
+    if: github.event.pull_request.head.repo.fork == false
     runs-on: "ubuntu-latest"
     continue-on-error: ${{ contains(fromJson('["puppetlabs","puppet-toy-chest"]'), github.repository_owner) != true }}
     steps: