Don't use cache dir for pip (#67)

For example, see IBM/MAX-Object-Detector#163

Author: xuhdev

Dockerfile

@@ -26,4 +26,4 @@ WORKDIR /home/max
 RUN mkdir assets
 COPY . .
 RUN conda install python==3.7.11
-RUN pip install --upgrade pip && pip install -r requirements.txt
+RUN pip install --no-cache-dir --upgrade pip && pip install --no-cache-dir -r requirements.txt

Dockerfile.arm32v7

@@ -31,5 +31,5 @@ WORKDIR /home/max
 RUN mkdir assets
 
 COPY . .
-RUN pip install --upgrade pip && pip install -r requirements.txt
+RUN pip install --no-cache-dir --upgrade pip && pip install --no-cache-dir -r requirements.txt