CI workflow doesn't test builded version

[bonddim]

Builded version is checked in build job only with this step:

helm-diff/.github/workflows/ci.yaml

Lines 38 to 42 in 882b211

	- name: Verify installation
	run: |
	mkdir -p helmhome
	make install HELM_HOME=helmhome
	helmhome/plugins/helm-diff/bin/diff version

Installing from plugin directory in helm-install and integration-tests jobs invokes install hook, which downloads binary from latest release:

helm-diff/.github/workflows/ci.yaml

Lines 93 to 94 in 882b211

	- name: helm plugin install
	run: helm plugin install .

helm-diff/.github/workflows/ci.yaml

Lines 113 to 114 in 882b211

	- name: helm plugin install
	run: helm plugin install .

Both these jobs are for testing install-binary.sh only and doesn't relate to binary itself.

It's better to move these tests to separate workflow like in #477 and write new jobs to test builded artifact on different OS-ARCH if needed.

[yxxhero]

done