fix requirements.txt filename in Dockerfile

flask_api/Dockerfile

@@ -5,7 +5,7 @@ LABEL maintainer="Oscar Leiva<oscar.leiva@mercadoselectricos.com.sv>"
 RUN mkdir -p /usr/src/app
 COPY requirements.txt /usr/src/app
 RUN pip install --upgrade pip
-RUN pip install -r /usr/src/app/requirements
+RUN pip install -r /usr/src/app/requirements.txt
 
 COPY ./app /usr/src/app