Remove references to non-existent branches.

.github/workflows/build.yml

@@ -4,9 +4,7 @@ name: 'Build'
 on:
   push:
     branches:
-      - master
       - main
-      - dev
   pull_request:
   schedule:
     - cron: "17 6 * * *"

.github/workflows/labeler.yml

@@ -4,7 +4,7 @@ name: Manage labels
 on:
   push:
     branches:
-      - master
+      - main
   workflow_dispatch:
 
 jobs:

.github/workflows/release-drafter.yml

@@ -4,7 +4,7 @@ name: Draft a release note
 on:
   push:
     branches:
-      - master
+      - main
   workflow_dispatch:
 
 jobs: