Update to 0.6.1

• Bump PORTREVISION for package change (in case users downloaded the wrong tarball)

Upstream made a wrong 0.6.1 release [1] and it's fixed now.

Reported by: Herbert J. Skuhra <herbert@gojira.at>
Reference: https://github.com/PJK/libcbor/commit/6f85e04aa770a2c3843e1851ec57adaf9481c3cb [1]