default_configs: docker-compose buildfails: ERROR: Could not find a version that satisfies the requirement label-studio-ml==2.0

```
docker-compose build
Building ml-backend
Sending build context to Docker daemon 12.29kB
Step 1/8 : FROM python:3.8-slim
---> 99f5de4b63d9
Step 2/8 : RUN apt-get update && apt-get upgrade -y && apt-get install -y git
---> Using cache
---> a409064926f3
Step 3/8 : ENV PYTHONUNBUFFERED=True PORT=9090 WORKERS=2 THREADS=4
---> Running in f39a9d4e79d1
Removing intermediate container f39a9d4e79d1
---> a1f21a3204a3
Step 4/8 : WORKDIR /app
---> Running in 4097afac9fb2
Removing intermediate container 4097afac9fb2
---> 7b0a71814823
Step 5/8 : COPY requirements.txt .
---> 0203d1d4e18e
Step 6/8 : RUN pip install --no-cache-dir -r requirements.txt
---> Running in 6b15aa55de62
Collecting gunicorn==20.1.0
Downloading gunicorn-20.1.0-py3-none-any.whl (79 kB)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 79.5/79.5 kB 5.3 MB/s eta 0:00:00
ERROR: Could not find a version that satisfies the requirement label-studio-ml==2.0 (from versions: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.0.4, 1.0.5, 1.0.6, 1.0.7rc0, 1.0.7rc1, 1.0.7, 1.0.8rc0, 1.0.8rc1, 1.0.8rc2, 1.0.8rc3, 1.0.8, 1.0.9rc0, 1.0.9rc1, 1.0.9)
ERROR: No matching distribution found for label-studio-ml==2.0

[notice] A new release of pip is available: 23.0.1 -> 23.2.1
[notice] To update, run: pip install --upgrade pip
The command '/bin/sh -c pip install --no-cache-dir -r requirements.txt' returned a non-zero code: 1
ERROR: Service 'ml-backend' failed to build : Build failed
```


Fix is in requirements.txt

gunicorn==20.1.0
label-studio-ml==**1.0.9**