upgrade pip

Dockerfile

@@ -14,7 +14,7 @@ RUN apt-get update && apt-get install -y git ffmpeg aria2 \
     && rm -rf /var/lib/apt/lists/* 
 
 COPY requirements.txt .
-RUN python -m pip install -upgrade pip
+RUN python -m pip install pip -U
 RUN pip install --no-cache-dir -r requirements.txt
 
 # Copy the application code