Fix email sending templating bug

[yanokwa]

Closes #454

What has been done to verify that this works as intended?

I ran docker compose config | grep EMAIL_FROM to see what the config was.

• with EMAIL_FROM in .env set to [email protected], I get [email protected] in the output.
• with EMAIL_FROM in .env commented out, I get [email protected] in the output.

I also confirmed that emails are delivered with this change.

Why is this the best possible solution? Were any other approaches considered?

There might be a bug in docker/compose v2.20.2/24.0.5, but thankfully https://docs.docker.com/compose/environment-variables/env-file/#parameter-expansion says unbraced vars are supported, so that's why this change works.

How does this change affect users? Describe intentional changes to behavior and behavior that could have accidentally been affected by code changes. In other words, what are the regression risks?

It should only affect people who might have changed docker-compose.yml. If something's broken when they upgrade, it will be pretty easy to see because they can't create or reset web users. Hopefully that will lead to a forum post or this issuel.

Does this change require updates to documentation? If so, please file an issue here and include the link below.

Before submitting this PR, please make sure you have:

• verified that any code or assets from external sources are properly credited in comments or that everything is internally sourced

[lognaturel]

I'm annoyed! But also glad there's an easily-verifiable fix.

[matthew-white]

Are we thinking of releasing this change with .4? Or are we planning to merge to the master branch before .4 (as a patch release)?

[yanokwa]

If we are already doing a hot fix, great. If not, it can wait.

[matthew-white]

Sounds good. There's a chance we'll have a hot fix coming up, so I won't merge to next quite yet, as next already has a change for .4. I can merge once we know whether we'll have a hot fix.

[matthew-white]

I now think it's less likely that we'll need a hot fix, so I'll go ahead and merge. I'll merge with a merge commit so that it's easy to include the commit in a hot fix if that does end up happening.