dependencies.yaml: Fixup golang regex for minor versions
dependencies.yaml: Fixup golang regex for minor versions

Upstream Golang uses the forms 'go1.15' and '1.15' to represent minor
releases (as opposed to 'go1.15.0' and '1.15.0').

Here we make the '.z' patch version optional in the regex.

Signed-off-by: Stephen Augustus <f96984fef9637085f0559f1484dfd4e99545cd6e@vmware.com>

kubernetes/release,kubernetes/release