Move build condition into separate stages list

.travis.yml

@@ -3,6 +3,12 @@ language: python
 dist: focal
 os: linux
 
+stages:
+ - name: build_docker
+   if: branch =~ /^(master|dev|ng-.*)$/
+ - name: publish_manifest
+   if: branch =~ /^(master|dev|ng-.*)$/
+
 jobs:
   include:
     - name: "Paperless on Python 3.6"
@@ -47,8 +53,6 @@ jobs:
         - echo "$DOCKER_PASSWORD" | docker login -u "$DOCKER_USERNAME" --password-stdin
         - docker build -f Dockerfile --tag=${DOCKER_REPO}:${TRAVIS_COMMIT}-amd64 .
         - docker push ${DOCKER_REPO}:${TRAVIS_COMMIT}-amd64
-      on:
-        condition: '"${BUILD_DOCKER}" = 1 and ( branch =~ /^(master|dev|ng-.*)$/)'
     - stage: build_docker
       name: arm64v8 docker build
       services:
@@ -67,8 +71,6 @@ jobs:
       arch: arm64-graviton2
       virt: vm
       group: edge
-      on:
-        condition: '"${BUILD_DOCKER}" = 1 and ( branch =~ /^(master|dev|ng-.*)$/)'
     - stage: build_docker
       name: arm32v7 docker build
       services:
@@ -92,8 +94,6 @@ jobs:
         - docker push ${DOCKER_REPO}:${TRAVIS_COMMIT}-arm32v7
       env:
         - DOCKER_CLI_EXPERIMENTAL=enabled # required for manifest support
-      on:
-        condition: '"${BUILD_DOCKER}" = 1 and ( branch =~ /^(master|dev|ng-.*)$/)'
     - stage: publish_manifest
       env:
         - DOCKER_CLI_EXPERIMENTAL=enabled # required for manifest support
@@ -128,8 +128,6 @@ jobs:
           else
             echo "Not a tag and not on master, so not pushing tag/master specific manifest"
           fi
-      on:
-        condition: '"${BUILD_DOCKER}" = 1 and ( branch =~ /^(master|dev|ng-.*)$/)'
 
 
 before_install: