Bump Go version to v1.20 (#24439)

.github/workflows/migration.yml

@@ -7,8 +7,7 @@ jobs:
       runs-on: ubuntu-22.04
       env:
           COMPOSE_PROJECT_NAME: ghactions
-          BUILD_IMAGE: mattermost/mattermost-build-server:20230118_golang-1.19.5
-          TEST_IMAGE: migration-test-image
+          BUILD_IMAGE: mattermost/mattermost-build-server:20230904_golang-1.20.7
       defaults:
         run:
           working-directory: server
@@ -21,10 +20,6 @@ jobs:
           docker-compose --ansi never run --rm start_dependencies
           docker-compose --ansi never exec -T minio sh -c 'mkdir -p /data/mattermost-test';
           docker-compose --ansi never ps
-      - name: Build test image
-        run: |
-          echo -e "FROM $BUILD_IMAGE\n\nRUN apt update && apt install -y pgloader" >> dockerfile_tmp
-          docker build -t $TEST_IMAGE - < dockerfile_tmp
       - name: Generate test-data
         run: |
           docker run --net ${COMPOSE_PROJECT_NAME}_mm-test \
@@ -34,7 +29,7 @@ jobs:
             -e GOCACHE=/go/cache \
             -v $PWD:/mattermost \
             -w /mattermost \
-            $TEST_IMAGE \
+            $BUILD_IMAGE \
             make test-data
       - name: Migrate the DB and compare
         run: |
@@ -45,7 +40,7 @@ jobs:
            -e GOCACHE=/go/cache \
            -v $PWD:/mattermost \
            -w /mattermost \
-           $TEST_IMAGE \
+           $BUILD_IMAGE \
            make test-migration
       - name: Upload artifacts
         uses: actions/upload-artifact@0b7f8abb1508181956e8e162db84b466c27e18ce # v3.1.2