Rollback helm library to version not failing v3 charts

Rollback helm library to version not failing v3 charts

This change reverts fef2f1a959341d2abaea6dadaecccc4952c284c9 commit that
updated helm library to a version, that no longer allowed helm v3 charts
by explicitly failing when parsing them. Proper support of helm v3 is
still not implemented in k8splugin, but at least it shouldn't fail on v3
packages that don't implement v3-specific features.
Also apart from revert, go.mod/sum have been also tidied.

Issue-ID: MULTICLOUD-1267
Signed-off-by: Konrad Bańka <k.banka@samsung.com>
Change-Id: I992004d30802134039f0a6aca2d07a42db9c2459