contrib: Improve version matching in readme bump
contrib: Improve version matching in readme bump

The previous version didn't prepend `v` to the version numbers, which
meant that it could end up unintentionally matching other text that
isn't version numbers, since the period characters in the versions are
not escaped (and are hence treated as wildcards by sed). Implement the
simple fix and just prepend the 'v' before the version so that the
substitutions are implemented correctly.

Signed-off-by: Joe Stringer <16a9a54ddf4259952e3c118c763138e83693d7fd@cilium.io>

michi-covalent/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium/cilium,cilium/cilium,michi-covalent/cilium,cilium/cilium,cilium/cilium,cilium/cilium,michi-covalent/cilium