[BUG] env_file property on include top-level element is relative to current directory instead of the directory of compose.yml

[jcoll-busup]

Description

The documentation for the include top-level element states the following about the env_file property:

env_file defines an environment file(s) to use to define default values when interpolating variables in the Compose file being parsed. It defaults to .env file in the project_directory for the Compose file being parsed.

env_file can be set either to a string or a list of strings when multiple environment files need to be merged to define a project environment.

Knowing that compose will use the .env file found on the project_directory, one would expect it to do the same for the environment files defined on the include top-level element (making use of the project_directory as relative path for env_file).

Yet, in practice it only will look at the current working directory and stop there, showing an error similar to this:
Couldn't find env file: .../.env.defaults.

This makes the env_file property kind of useless, as it will break the usage of the compose config from anywhere but the project root.

I think this may be related to issues #11392 and #11405.

Steps To Reproduce

1. Create the following project structure:

compose-example/
  - compose.yml
  - include/
    - main.yml
    - .env.main

2. Recreate the files with the following content:

# compose.yml
include:
  - path: include/main.yml
    project_directory: ./
    env_file: include/.env.main

# include/main.yml
services:
  hello-world:
    image: ${HELLO_WORLD_IMAGE}
    network_mode: none

# include/.env.main
HELLO_WORLD_IMAGE=hello-world:latest

3. Run the hello-world container from the project root, which should work fine:
   docker compose run hello-world

4. Enter into a subdirectory and repeat the previous command; it will fail with a message similar to this one: "Couldn't find env file: include/.env.main"
   cd include && docker compose run hello-world

Compose Version

Docker Compose version v2.24.6

Docker Environment

Client: Docker Engine - Community
 Version:    25.0.3
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.12.1
    Path:     /usr/libexec/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.24.6
    Path:     /usr/libexec/docker/cli-plugins/docker-compose

Server:
 Containers: 22
  Running: 21
  Paused: 0
  Stopped: 1
 Images: 35
 Server Version: 25.0.3
 Storage Driver: btrfs
  Btrfs: 
 Logging Driver: json-file
 Cgroup Driver: systemd
 Cgroup Version: 2
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local splunk syslog
 Swarm: active
  NodeID: ol81y1nxwbxehpwrg3y85p6sl
  Is Manager: true
  ClusterID: lnx9q652c5ilk8ezx27s5zhs3
  Managers: 1
  Nodes: 1
  Default Address Pool: 10.0.0.0/8  
  SubnetSize: 24
  Data Path Port: 4789
  Orchestration:
   Task History Retention Limit: 5
  Raft:
   Snapshot Interval: 10000
   Number of Old Snapshots to Retain: 0
   Heartbeat Tick: 1
   Election Tick: 10
  Dispatcher:
   Heartbeat Period: 5 seconds
  CA Configuration:
   Expiry Duration: 3 months
   Force Rotate: 0
  Autolock Managers: false
  Root Rotation In Progress: false
  Node Address: 192.168.1.25
  Manager Addresses:
   192.168.1.25:2377
 Runtimes: io.containerd.runc.v2 runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: ae07eda36dd25f8a1b98dfbf587313b99c0190bb
 runc version: v1.1.12-0-g51d5e94
 init version: de40ad0
 Security Options:
  apparmor
  seccomp
   Profile: builtin
  cgroupns
 Kernel Version: 6.5.0-21-generic
 Operating System: Ubuntu 23.10
 OSType: linux
 Architecture: x86_64
 CPUs: 4
 Total Memory: 15.54GiB
 Name: silver-wolf
 ID: 67QL:C3EK:7DPH:V6KP:3OSW:E2E7:QUMX:VWJS:4K7S:R2XC:IZY3:IPGO
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Experimental: false
 Insecure Registries:
  127.0.0.0/8
 Live Restore Enabled: false

Anything else?

No response

[ndeloof]

already fixed by compose-spec/compose-go#593