Update the docker image from golang:1.22.3-alpine3.18 to golang:1.22.4-alpine3.20

[edwbuck]

When building the images from the Makefile, I noticed that our Docker image references Alpine Linux version 3.18. There are a few trivial (low impact) CVEs in Alpine 3.18, and it might be a good idea to update to Alpine 3.20.

I noticed in the comments that we chose not to update to Alpine 3.19 due to issues in go-sqlite. I am hoping that they are resolved with either the 1.22.3 -> 1.22.4 transition or the Alpine 3.18 -> Alpine 3.20 transition.

[nweisenauer-sap]

Looking forward to an updated Go version as well, the currently used version (1.22.3) suffers from a CVE with a rating of 9.8 according to nist. Not saying that this one is actually exploitable here (I did not verify), but it shows in scans nevertheless.