Fix helm dependency build once and for all (#535)

### Description of the change

We are affected by a regression of a Helm bug from May 2023. I've tested
the Helm versions 3.13.1, 3.13.0 and 3.12.3. Both 3.13.x are affected.
3.12.3 works. So let's downgrade and drop the docker login in PR builds.

I've also switched the `apt install helm` with an official `alpine/helm`
image I am using at work. Pinning the helm version and receiving updates
helps us identifying such issues in the future.

For the release workflow I was a bit more reluctant with changes, since
I cannot easily test them. That's why I just pinned the Helm version.

Renovate will provide one PR changing both files because it's the same
dependency (alpine/helm) from the same datasource (docker).

https://github.com/helm/helm/issues/12062

### Applicable issues

- implicitly fixes #527

Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/535
Reviewed-by: pat-s <pat-s@noreply.gitea.com>
Co-authored-by: justusbunsi <sk.bunsenbrenner@gmail.com>
Co-committed-by: justusbunsi <sk.bunsenbrenner@gmail.com>

.gitea/workflows/release-version.yml

@@ -5,6 +5,10 @@ on:
     tags:
       - "*"
 
+env:
+  # renovate: datasource=docker depName=alpine/helm
+  HELM_VERSION: "3.12.3"
+
 jobs:
   generate-chart-publish:
     runs-on: ubuntu-latest
@@ -23,7 +27,7 @@ jobs:
           chmod a+r /etc/apt/keyrings/docker.gpg
           echo "deb [arch="$(dpkg --print-architecture)" signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/debian "$(. /etc/os-release && echo "$VERSION_CODENAME")" stable" | tee /etc/apt/sources.list.d/docker.list > /dev/null
           apt update -y
-          apt install -y python helm python3-pip apt-transport-https docker-ce-cli
+          apt install -y python helm=${{ env.HELM_VERSION }}-1 python3-pip apt-transport-https docker-ce-cli
           pip install awscli
 
       - name: Import GPG key