This is not needed to fix #59. In fact, this is IMO not a good solution because it tightens the dependency requirement to just 1.5.x (where x >= 0). It also drops the support for mint 1.4, although it works perfectly fine.

The proper solution is to bump the dependency in the client project. Going to the client project root and running mix deps.unlock mint, followed by mix deps.get should probably do the job, modifying only mix.exs in the process.

Clear, thank you for the clarification. 🙇‍♂️
I'm closing the PR in that case.

I also have to share the good news that the fix indeed worked:

✲ NEWDEV ~/code/operately (site-encrypt) ./devenv mix phx.server
14:32:45.297 [info] Running OperatelyWeb.Endpoint with cowboy 2.12.0 at 0.0.0.0:4000 (http)
14:32:45.338 [info] Running OperatelyWeb.Endpoint with cowboy 2.12.0 at 0.0.0.0:4001 (https)
14:32:45.341 [info] Access OperatelyWeb.Endpoint at https://localhost:4001
14:32:45.343 [info] Running local ACME server at port 4002
0.14.54
14:32:45.431 [info] Certificate for localhost is valid until 3023-10-02. Next renewal is scheduled for 3023-09-02.

🎉