Install bash for proper pipefail error handling

Dockerfile

@@ -13,6 +13,7 @@ COPY ./test/pytest/le-staging-bundle.pem /usr/local/share/ca-certificates/le-sta
 COPY ./requirements.txt /requirements.txt
 RUN \
   apk --no-cache add \
+    bash=5.1.0-r0 \
     cargo=~1.47.0-r2 \
     chromium=~86.0.4240.111-r0 \
     chromium-chromedriver=~86.0.4240.111-r0 \