ci: remove stale ci/spell-checker configuration (#519)

diff --git a/.github/workflows/spell-checker.yml b/.github/workflows/spell-checker.yml
index a0e3aa6..a536334 100644
--- a/.github/workflows/spell-checker.yml
+++ b/.github/workflows/spell-checker.yml
@@ -19,7 +19,7 @@
 name: spell-checker
 on:
   push:
-    branches: [ master, ci/spell-checker ]
+    branches: [ master ]
   pull_request:
     branches: [ master ]
 jobs: