workflows/no-channel: fix typo (#405001)

Author: mweinelt

.github/workflows/no-channel.yml

@@ -12,7 +12,7 @@ jobs:
     if: |
       startsWith(github.event.pull_request.base.ref, 'nixos-') ||
       startsWith(github.event.pull_request.base.ref, 'nixpkgs-')
-    name: "This PR is is targeting a channel branch"
+    name: "This PR is targeting a channel branch"
     runs-on: ubuntu-24.04
     steps:
       - run: |