Update Dockerfile to install Python 3.12 venv and bootstrap pip

- Replaced python3-pip with python3.12-venv in the installation process.
- Added commands to ensure pip is upgraded and installed after setting Python 3.12 as the default.
- Streamlined the installation of PyTorch by removing redundant pip upgrade command.

Dockerfile.cuda

@@ -15,15 +15,17 @@ RUN apt-get update && apt-get install -y \
     && apt-get update && apt-get install -y \
     python3.12 \
     python3.12-dev \
-    python3-pip \
+    python3.12-venv \
     ffmpeg \
     curl \
     tzdata \
     && rm -rf /var/lib/apt/lists/*
 
-# Set Python 3.12 as default
+# Set Python 3.12 as default and bootstrap pip
 RUN update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.12 1 && \
-    update-alternatives --install /usr/bin/python python /usr/bin/python3.12 1
+    update-alternatives --install /usr/bin/python python /usr/bin/python3.12 1 && \
+    python3.12 -m ensurepip --upgrade && \
+    python3.12 -m pip install --upgrade pip
 
 # Copy backend
 COPY backend/ /app/backend/
@@ -33,8 +35,7 @@ COPY providers/ /app/providers/
 COPY web/dist/ /app/web/dist/
 
 # Install PyTorch with CUDA support first
-RUN python -m pip install --upgrade pip && \
+RUN pip install --no-cache-dir \
-    pip install --no-cache-dir \
     torch torchvision torchaudio --index-url https://download.pytorch.org/whl/cu121
 
 # Install remaining dependencies