Installation procedure fails with helm v3.4.0

[gberche-orange]

Describe the bug

As a user

• in order to use hcunit
• I need to install it

To Reproduce

Steps to reproduce the behavior:

1. Follow procedure at https://github.com/xchapter7x/hcunit#usage-as-a-helm-plugin
2. Execute helm plugin install https://github.com/xchapter7x/hcunit/releases/latest/download/hcunit_plugin.tgz

Expected behavior

A clear and concise description of what you expected to happen.

Installed plugin: unit

Observed behavior

$ helm plugin install https://github.com/xchapter7x/hcunit/releases/latest/download/hcunit_plugin.tgz
Error: Unable to get repository: Cloning into '/data/shared/gberche/.cache/helm/plugins/https-github.com-xchapter7x-hcunit-releases-latest-download-hcunit_plugin.tgz'...
remote: Please upgrade your git client.
remote: GitHub.com no longer supports git over dumb-http: https://github.com/blog/809-git-dumb-http-transport-to-be-turned-off-in-90-days
fatal: unable to access 'https://github.com/xchapter7x/hcunit/releases/latest/download/hcunit_plugin.tgz/': The requested URL returned error: 403
: exit status 128

I also tried to download the plugin and install it locally

$  curl -LO https://github.com/xchapter7x/hcunit/releases/latest/download/hcunit_plugin.tgz
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   145  100   145    0     0    368      0 --:--:-- --:--:-- --:--:--   368
100   643  100   643    0     0   1030      0 --:--:-- --:--:-- --:--:--  1030
100 22.9M  100 22.9M    0     0   343k      0  0:01:08  0:01:08 --:--:--  277k

$ helm plugin install --debug ./hcunit_plugin.tgz

Error: plugin metadata (plugin.yaml) missing
helm.go:81: [debug] plugin metadata (plugin.yaml) missing
helm.sh/helm/v3/pkg/plugin/installer.init
	/home/circleci/helm.sh/helm/pkg/plugin/installer/installer.go:32
runtime.doInit
	/usr/local/go/src/runtime/proc.go:5453
runtime.doInit
	/usr/local/go/src/runtime/proc.go:5448
runtime.main
	/usr/local/go/src/runtime/proc.go:190
runtime.goexit
	/usr/local/go/src/runtime/asm_amd64.s:1373

I also tried the git repo syntax

$ helm plugin install https://github.com/xchapter7x/hcunit --version v0.7.5
Error: plugin metadata (plugin.yaml) missing

workaround

$  curl -LO https://github.com/xchapter7x/hcunit/releases/latest/download/hcunit_plugin.tgz
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   145  100   145    0     0    368      0 --:--:-- --:--:-- --:--:--   368
100   643  100   643    0     0   1030      0 --:--:-- --:--:-- --:--:--  1030
100 22.9M  100 22.9M    0     0   343k      0  0:01:08  0:01:08 --:--:--  277k

$ mkdir hcunit_plugin
$ (cd hcunit_plugin;  tar xvfz  ./hcunit_plugin.tgz)
$ helm plugin install --debug ./hcunit_plugin
Installed plugin: unit

Desktop (please complete the following information):

• OS: "Ubuntu 18.04.5 LTS" (bionic)
• Browser [e.g. chrome, safari]
• helm version: version.BuildInfo{Version:"v3.4.0", GitCommit:"7090a89efc8a18f3d8178bf47d2462450349a004", GitTreeState:"clean", GoVersion:"go1.14.10"}

Additional context Add any other context about the problem here.