DEV: Remove references to deprecated main branch

DEV: Remove references to deprecated main branch

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 4521508..7ef3360 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -1,7 +1,6 @@
 on:
   push:
     branches:
-      - master
       - main
   pull_request:
   schedule:
@@ -16,7 +15,7 @@ jobs:
           sudo bash -c 'echo "{ \"cgroup-parent\": \"/actions_job\",\"experimental\":true}" > /etc/docker/daemon.json'
           sudo service docker restart
           docker version -f '{{.Server.Experimental}}'
-      - uses: actions/checkout@master
+      - uses: actions/checkout@v2
         with:
           fetch-depth: 1
       - name: build base image
@@ -29,7 +28,7 @@ jobs:
         run: |
           docker run --rm -e RUBY_ONLY=1 -e USE_TURBO=1 -e SKIP_PLUGINS=1 -e SKIP_LINT=1 discourse/discourse_test:build
       - name: push to dockerhub
-        if: success() && (github.ref == 'refs/heads/main' || github.ref == 'refs/heads/master')
+        if: success() && (github.ref == 'refs/heads/main')
         env:
           DOCKERHUB_PASSWORD: ${{ secrets.DOCKERHUB_PASSWORD }}
         run: |
@@ -48,14 +47,14 @@ jobs:
           sudo bash -c 'echo "{ \"cgroup-parent\": \"/actions_job\",\"experimental\":true}" > /etc/docker/daemon.json'
           sudo service docker restart
           docker version -f '{{.Server.Experimental}}'
-      - uses: actions/checkout@master
+      - uses: actions/checkout@v2
         with:
           fetch-depth: 1
       - name: build discourse_test image
         run: |
           cd image && ruby auto_build.rb discourse_test_public
       - name: push to dockerhub
-        if: success() && (github.ref == 'refs/heads/main' || github.ref == 'refs/heads/master')
+        if: success() && (github.ref == 'refs/heads/main')
         env:
           DOCKERHUB_PASSWORD: ${{ secrets.DOCKERHUB_PASSWORD }}
         run: |
@@ -65,14 +64,14 @@ jobs:
     runs-on: [ubuntu-20.04]
     needs: base
     steps:
-      - uses: actions/checkout@master
+      - uses: actions/checkout@v2
         with:
           fetch-depth: 1
       - name: build discourse_dev image
         run: |
           cd image && ruby auto_build.rb discourse_dev
       - name: push to dockerhub
-        if: success() && (github.ref == 'refs/heads/main' || github.ref == 'refs/heads/master')
+        if: success() && (github.ref == 'refs/heads/main')
         env:
           DOCKERHUB_PASSWORD: ${{ secrets.DOCKERHUB_PASSWORD }}
         run: |

GitHub sha: e774d9e112867f67f28162ec7decbb74a1ace5ae

This commit appears in #561 which was approved by pmusaraj. It was merged by Falco.