fix(ci): improve workflows (#959)

🤖 Split up helm chart workflows

The following patch adapts the CI workflows. The worflows has been splitted into
dedicated parts. For example the `helm template` and `helm unittest` command is
now a seperate step to notice that a change affects the template mechanism but
not the unittest. This was priviously not possible, because both commands were
part of one step.

🤖 Changelog Issue

Additionally has the changelog workflow be improved. The shell commands has
been migrated to a dedicated file named `.gitea/scripts/changelog.sh`. This has
the advantage, that the shellcheck plugin of IDE's support developers by
developing such shell scripts. Furthermore, the used container image has been
replaced by the ubuntu:latest image of the act_runner. This make it more
comfortable in using `curl` or `jq`, because the complete set of features/flags
are
avialable instead of the previously used container image
`docker.io/thegeeklab/git-sv:2.0.5`. Final note to the shell script
`changelog.sh`, this can now be executed locally as well as on ARM-based
act_runners and helps to test the helm chart in own Gitea environments
beforehand.

🤖 Markdown linter

In addition, a new workflow for markdown files has now been introduced. This
checks the `README.md` file for links, ensures that it is properly formatted,
and verifies that the parameters match those in `values.yaml`. Here, too, the
commands have been outsourced to separate jobs so that more precise interaction
is possible in the event of an error.

⚠️ Warning

This patch also requires an adjustment in branch protection. There, the
workflows that must be successful before a merge must be redefined.

Reviewed-on: https://gitea.com/gitea/helm-gitea/pulls/959
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Markus Pesch <markus.pesch@cryptic.systems>
Co-committed-by: Markus Pesch <markus.pesch@cryptic.systems>

README.md

@@ -17,7 +17,7 @@
     - [Rootless Defaults](#rootless-defaults)
     - [Session, Cache and Queue](#session-cache-and-queue)
   - [Single-Pod Configurations](#single-pod-configurations)
-  - [Additional _app.ini_ settings](#additional-appini-settings)
+  - [Additional app.ini settings](#additional-appini-settings)
     - [User defined environment variables in app.ini](#user-defined-environment-variables-in-appini)
   - [External Database](#external-database)
   - [Ports and external url](#ports-and-external-url)
@@ -72,7 +72,7 @@ Additionally, this chart allows to provide LDAP and admin user configuration wit
 ## Update and versioning policy
 
 The Gitea helm chart versioning does not follow Gitea's versioning.
-The latest chart version can be looked up in [https://dl.gitea.com/charts](https://dl.gitea.com/charts) or in the [repository releases](https://gitea.com/gitea/helm-gitea/releases).
+The latest chart version can be looked up in [https://dl.gitea.com/charts/](https://dl.gitea.com/charts/) or in the [repository releases](https://gitea.com/gitea/helm-gitea/releases).
 
 The chart aims to follow Gitea's releases closely.
 There might be times when the chart is behind the latest Gitea release.
@@ -360,7 +360,7 @@ If HA is not needed/desired, the following configurations can be used to deploy
 
    </details>
 
-### Additional _app.ini_ settings
+### Additional app.ini settings
 
 > **The [generic](https://docs.gitea.com/administration/config-cheat-sheet#overall-default)
 > section cannot be defined that way.**