Merge branch 'fix-dockerfile' into 'master'

`pip install` now uses `requirements.txt` inside the `Dockerfile`

See merge request ix.ai/etherscan-exporter!8

Author: tlex

Dockerfile

@@ -10,7 +10,7 @@ COPY src/ /app
 
 RUN apk --no-cache upgrade && \
     apk add --no-cache python3 gcc musl-dev && \
-    pip3 install --no-cache-dir prometheus_client pygelf requests && \
+    pip3 install --no-cache-dir -r requirements.txt && \
     apk del --no-cache --purge gcc musl-dev
 
 ENV LOGLEVEL=${LOGLEVEL} PORT=${PORT}