depends_on: does not check if service exists

**Describe the bug**
the podman-compose starts a service even if the dependent service does not exist.

**To Reproduce**
Steps to reproduce the behavior:
```
cat /etc/redhat-release
Fedora release 40 (Forty)

cd /tmp
mkdir ./1

cat ./1.yml
services:
**service1**:
image: nginx
environment:
- PORT=3000
ports:
- "3000:3000"

**service2**:
image: nginx
environment:
- PORT=3001
ports:
- "3001:3001"
depends_on:
**serviceBLAH:**
condition: service_started

```

**Expected behavior**
I expected some sanity/validation check if the service in "depends" exists.

**Actual behavior**
service2 starts

**Output**

```
podman-compose -v
podman-compose version 1.2.0
podman version 5.3.1

...

```

**Environment:**
cat /etc/redhat-release
Fedora release 40 (Forty)

Start by reproducing the missing-service case from the issue with podman-compose and trace the depends_on handling for the serviceBLAH entry. Add validation so a dependency that is not defined is rejected, then run the relevant existing compose tests or add coverage showing service2 does not start.

Written by the indexing model from the issue text.