Update GitHub actions to reference 'main' instead of 'master' (#2460)

Author: bkonyi

.github/workflows/changelog_reminder.yml

@@ -18,8 +18,8 @@ jobs:
         uses: actions/checkout@44c2b7a8a4ea60a981eaca3cf939b5f4305c123b
       - name: Check changed files
         run: |
-          git fetch origin master
-          PR_DIFF=$(git diff origin/master --name-only)
+          git fetch origin main
+          PR_DIFF=$(git diff origin/main --name-only)
           echo "$PR_DIFF"
           if [[ $PR_DIFF == *"CHANGELOG.md"* ]]; then
             echo "CHANGELOG.md has been updated."

.github/workflows/dcm.yml

@@ -6,7 +6,7 @@ on:
   pull_request:
     types: [synchronize, opened, reopened]
     branches:
-      - master
+      - main
 
 jobs:
   dcm:

.github/workflows/publish.yaml

@@ -4,7 +4,7 @@ name: Publish
 
 on:
   pull_request:
-    branches: [ master ]
+    branches: [ main ]
     types: [opened, synchronize, reopened, labeled, unlabeled]
   push:
     tags: [ '[A-z]+-v[0-9]+.[0-9]+.[0-9]+*' ]