Drop template export semver compat with versions prior to 0.12.1 (retry)

We want to update all our tests to use the new syntax. That means we must bump the tests' old version of d-d to 0.12.1. That means we're not testing compatibility with earlier versions.

This is a revised version of !429 (merged) which gitlab tricked me into merging despite a CI failure. I have rewritten the bottom commit so we get a full every-commit test on this branch.

I intend to get CI to pass on this, and then merge it. I think the merge will be treesame to this MR tip, but I will check.

assigned to @Diziet

!428 (merged) merged in the meantime so the merge won't be pseudomerge-like. Bah. Still there will be a bisection path for every test case, maybe?

added 3 commits

• 9878ce10 - Drop template export semver compat with versions prior to 0.12.1
• ce0806b8 - Handle UNRELEASED when parsing the changelog for semver version
• 1e1c061b - Document the semver situation in the CHANGELOG

Compare with previous version

enabled an automatic merge when the pipeline for 1e1c061b succeeds

mentioned in commit daaec56f

merged

mentioned in issue #95 (closed)

mentioned in issue #80 (closed)