Automate gather right dependencies for helm-operator

[onedr0p]

We can use the following files to get the correct version of each one

• https://github.com/fluxcd/helm-operator/blob/master/docker/helm2.version
• https://github.com/fluxcd/helm-operator/blob/master/docker/helm3.version
• https://github.com/fluxcd/helm-operator/blob/master/docker/kubectl.version

Then export the variables in each with

RUN \
	export HELM2_VERSION =$(echo "$(cut -d'=' -f2 <<< $(grep HELM2_VERSION ./docker/helm2.version))") && \
    export HELM3_VERSION =$(echo "$(cut -d'=' -f2 <<< $(grep HELM3_VERSION ./docker/helm3.version))") && \
    export KUBECTL_VERSION =$(echo "$(cut -d'=' -f2 <<< $(grep KUBECTL_VERSION ./docker/kubectl.version))") && \
...