workflows: change "master" to "main"

Signed-off-by: Ramkumar Chinchani <rchincha@cisco.com>

.github/workflows/ci-cd.yml

@@ -1,10 +1,10 @@
 on:
   push:
     branches: 
-      - master
+      - main
   pull_request:
     branches:
-      - master
+      - main
   release:
     types:
       - published

.github/workflows/codeql-analysis.yml

@@ -13,10 +13,10 @@ 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: '17 11 * * 0'
 
@@ -68,4 +68,4 @@ jobs:
     #   make release
 
     - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@v1
+      uses: github/codeql-action/analyze@v1

.github/workflows/dco.yml

@@ -4,7 +4,7 @@ on:
   pull_request:
   push:
     branches:
-      - master
+      - main
 jobs:
   check:
     runs-on: ubuntu-latest

.github/workflows/oci-conformance-action.yml

@@ -7,10 +7,10 @@ name: conformance
 on:
   push:
     branches: 
-      - master
+      - main
   pull_request:
     branches:
-      - master
+      - main
 
 # A workflow run is made up of one or more jobs that can run sequentially or in parallel
 jobs: