Fix Dockerfile

Dockerfile

@@ -3,9 +3,11 @@ FROM python:3.7
 ENV DEBIAN_FRONTEND=noninteractive \
     TERM=xterm
 
+COPY requirements.txt /
+
 RUN set -e -o xtrace \
   ; pip install -U pip \
-  ; pip install -r requirements.txt
+  ; pip install -r /requirements.txt
 
 COPY scripts /