ci: fix typos in workflows

Author: atsyplenkov

.github/workflows/check-r-pkg.yaml

@@ -2,7 +2,7 @@
 # Need help debugging build failures? Start at https://github.com/r-lib/actions#where-to-find-help
 on:
   push:
-    branches: master]
+    branches: master
   pull_request:
     branches: master
 

.github/workflows/pkgcheck.yaml

@@ -8,11 +8,7 @@ concurrency:
 on:
   # Manually trigger the Action under Actions/pkgcheck
   workflow_dispatch:
-  # Run on every push to main
-  push:
-    branches:
-      - main
-      - master
+
 
 jobs:
   pkgcheck: