Maintenance: update existing CI/CD branch references following default branch name update

.circleci/config.yml

@@ -21,7 +21,7 @@ workflows:
       - plugin-ci/deploy-ci:
           filters:
             branches:
-              only: master
+              only: main
           context: plugin-ci
           requires:
             - plugin-ci/lint

.github/workflows/codeql-analysis.yml

@@ -2,10 +2,10 @@ name: "CodeQL"
 
 on:
   push:
-    branches: [ master ]
+    branches: [ main ]
   pull_request:
     # The branches below must be a subset of the branches above
-    branches: [ master ]
+    branches: [ main ]
   schedule:
     - cron: '30 0 * * 0'