jessie-backports does not have a Release file.

[Tom Brown]

make run-dev
failed with

Digest: sha256:3e4be41076ebb6fe8c3112b220ce133ef0dc49c814024e4874ca76eae3c8dec0
Status: Downloaded newer image for python:3.7-slim
 ---> 6ba8638f69d7
Step 2/10 : RUN echo 'deb http://http.debian.net/debian jessie-backports main' >> /etc/apt/sources.list     && apt-get update     && apt-get install -y --no-install-recommends apt-utils
 ---> Running in 7a47c384af2f
….
Ign:9 http://cdn-fastly.deb.debian.org/debian jessie-backports/main amd64 Packages
Ign:11 http://http.debian.net/debian jessie-backports/main all Packages
Ign:11 http://cdn-fastly.deb.debian.org/debian jessie-backports/main all Packages
Err:9 http://http.debian.net/debian jessie-backports/main amd64 Packages
  404  Not Found
Ign:9 http://cdn-fastly.deb.debian.org/debian jessie-backports/main amd64 Packages
Ign:11 http://cdn-fastly.deb.debian.org/debian jessie-backports/main all Packages
Fetched 7885 kB in 4s (1626 kB/s)
Reading package lists...
W: The repository 'http://http.debian.net/debian jessie-backports Release' does not have a Release file.
E: Failed to fetch http://http.debian.net/debian/dists/jessie-backports/main/binary-amd64/Packages  404  Not Found

which I fixed by following https://unix.stackexchange.com/a/508728

diff --git a/Dockerfile b/Dockerfile
index f952ad9..f2a195f 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,6 +1,6 @@
 FROM python:3.7-slim
 
-RUN echo 'deb http://http.debian.net/debian jessie-backports main' >> /etc/apt/sources.list \
+RUN echo 'deb [check-valid-until=no] http://archive.debian.org/debian jessie-backports main' >> /etc/apt/sources.list \
     && apt-get update \
     && apt-get install -y --no-install-recommends apt-utils