Set main as default branch

.github/workflows/e2e.yaml

@@ -4,7 +4,7 @@ on:
   pull_request:
   push:
     branches:
-      - master
+      - main
 
 jobs:
   kind:

.github/workflows/fossa.yml

@@ -1,9 +1,9 @@
 name: FOSSA
 on:
   push:
-    branches: [master]
+    branches: [main]
   pull_request:
-    branches: [master]
+    branches: [main]
 
 jobs:
   build:

.github/workflows/release.yml

@@ -101,7 +101,7 @@ jobs:
           draft: false
           prerelease: true
           body: |
-            [CHANGELOG](https://github.com/fluxcd/notification-controller/blob/master/CHANGELOG.md)
+            [CHANGELOG](https://github.com/fluxcd/notification-controller/blob/main/CHANGELOG.md)
       - name: Upload artifacts
         if: github.event_name == 'push' && contains(github.ref, 'refs/tags/')
         id: upload-release-asset