Updated dependencies and used new safefile lib

Minor update: migrated external dependencies. Switched to improved safefile lib.
sigtool-v3.2.1_linux-amd64.tar.gz
sigtool-v3.2.1_linux-arm64.tar.gz
sigtool-v3.2.1_windows-amd64.tar.gz
sigtool-v3.2.1_windows-arm64.tar.gz
sigtool-v3.2.1_openbsd-amd64.tar.gz
sigtool-v3.2.1_openbsd-arm64.tar.gz
sigtool-v3.2.1_darwin-amd64.tar.gz
sigtool-v3.2.1_darwin-arm64.tar.gz

v3.2.0

Teach sigtool verify to understand public keys passed as a string on the command line (in lieu of a file).