Add --skip-pull support to v2 run command

The `docker-compose` plugin currently seems to ignore the `skip-pull`
option. For example, this configuration:

```
steps:
  - command: bundle exec rubocop
    plugins:
      - docker-compose#v4.14.0:
          run: ruby
          skip-pull: true
          config: docker-compose.yml
          cli-version: 2
```

Results in a command that includes the `--pull` flag, something like
this:

```
docker compose -f docker-compose.yml -p buildkite0123456789 build --pull ruby
```

This PR updates run.sh to fully support the `skip-pull` option. The
same configuration as above now results in the `--pull` flag being
omitted from the generated command:

```
docker compose -f docker-compose.yml -p buildkite0123456789 build ruby
```

commands/run.sh

@@ -271,7 +271,12 @@ fi
 
 run_params+=("$run_service")
 
-build_params=(--pull)
+build_params=()
+
+# Only pull if SKIP_PULL is not true
+if [[ ! "$(plugin_read_config SKIP_PULL "false")" == "true" ]] ; then
+  build_params+=(--pull)
+fi
 
 if [[ "$(plugin_read_config NO_CACHE "false")" == "true" ]] ; then
   build_params+=(--no-cache)

tests/v2/run.bats

@@ -259,6 +259,33 @@ cmd3"
   unstub buildkite-agent
 }
 
+@test "Run without a prebuilt image without pulling" {
+  export BUILDKITE_JOB_ID=1111
+  export BUILDKITE_PLUGIN_DOCKER_COMPOSE_RUN=myservice
+  export BUILDKITE_PIPELINE_SLUG=test
+  export BUILDKITE_BUILD_NUMBER=1
+  export BUILDKITE_COMMAND="echo hello world"
+  export BUILDKITE_PLUGIN_DOCKER_COMPOSE_CHECK_LINKED_CONTAINERS=false
+  export BUILDKITE_PLUGIN_DOCKER_COMPOSE_CLEANUP=false
+  export BUILDKITE_PLUGIN_DOCKER_COMPOSE_SKIP_PULL=true
+
+  stub docker \
+    "compose -f docker-compose.yml -p buildkite1111 build myservice : echo built myservice" \
+    "compose -f docker-compose.yml -p buildkite1111 up -d --scale myservice=0 myservice : echo ran myservice dependencies" \
+    "compose -f docker-compose.yml -p buildkite1111 run --name buildkite1111_myservice_build_1 --rm myservice /bin/sh -e -c 'echo hello world' : echo ran myservice"
+
+  stub buildkite-agent \
+    "meta-data exists docker-compose-plugin-built-image-tag-myservice : exit 1"
+
+  run "$PWD"/hooks/command
+
+  assert_success
+  assert_output --partial "built myservice"
+  assert_output --partial "ran myservice"
+  unstub docker
+  unstub buildkite-agent
+}
+
 @test "Run with a prebuilt image and propagate environment but no BUILDKITE_ENV_FILE" {
   export BUILDKITE_JOB_ID=1111
   export BUILDKITE_PIPELINE_SLUG=test