GitLab

No master, but main

See merge request !370

README: we're at 4.x now!

See merge request !371

README: headline: drop version

See merge request !368

ruby 2.1 support is gone

See merge request !369

CI: Transition to rules, instead of deprecated only/except clauses

Closes #469

See merge request !365

spec_helper: save simplecov output as HTML

See merge request !366

In most cases, relying on rules instead of only/except clauses offers
more possibilites.

This commit changes the CI pipeline configuration as follows:

- Pipelines are executed with the Ruby rspec jobs for all branches,
except if an associated MR exists.

- In this case, create a so called "detached pipeline" with all, the
Ruby rspec and MR-specific, jobs.

- Pipelines aren't executed for tags at all, as the relevant commits are
tested in any case.

This prevents duplicated pipelines and therefore wasted resources.

Besides this, the CHANGELOG job result gets more reliable: up until now,
the result of it was timing-sensitive, as it queried the GitLab API to
search for an associated MR, to get the target branch to compare
against. This would fail in case a branch was pushed, the job started
but a MR only created some time afterwards, as there would be no target
branch, yet.

Now, as the job is run within the "detached pipeline" of a MR, and
relies on the MR-specific target branch exposed via a variable, this job
isn't timing-sensitive anymore.

To ensure these changes do work as expected, they were extensively
tested in a forked repo.

Closes #469

Ref !287
Ref 2f779414

Collected changes for v4.0

Closes #286, #380, #174, #374, #411, and #422

See merge request !367

In case this check fails, it might give a hint that things might go
wrong. Accordingly, make this situation more obvious, so it doesn't slip
under the radar.

It seems this one was forgotten, while preparing the upcoming "small40"
release.

Ref 6bf26484
Ref !322

No one speaks about "Abonnements" in real life in German

key.key_summary is redundant, we don't need that. It feels strange to
type that into code.

Apparently an empty file doesn't lead to a migration-error anymore?

Those files were two digits short.

(cherry picked from commit f4fb7b91)

(cherry picked from commit 69de066b)

They don't work with activerecord 6, and served their purpose for a
previous update of schleuder. We don't need them anymore.

(cherry picked from commit 04956730)

Tempfile was extracted into a gem from stdlib for ruby3.0 It's easy
enough to replace it with manual code, to avoid a new dependency.

(cherry picked from commit a0a5c4f3)

Background:
<https://www.ruby-lang.org/en/news/2019/12/12/separation-of-positional-and-keyword-arguments-in-ruby-3-0/>.

(cherry picked from commit 2227c172)