Update protovalidate import path (#32)

The latest version of protovalidate has moved from github.com/bufbuild to a vanity URL in buf.build/go (in preparation for v1.0)

Chore update license file year and tools (#30)

Updates LICENSE and tools.
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Signed-off-by: Edward McFarlane <emcfarlane@buf.build>

Add release notes template (#8)