checkstring 0.2.1

is_base64(), is_base64url(), is_doi(), is_email(), is_ipv4(), is_iso_datetime(), is_mime(), is_semver(), and is_uuid() no longer accept strings with a trailing newline, such as "1.0.0\n".
is_base64() and is_base64url() now return FALSE for empty strings.
is_cuid2() now rejects strings longer than 32 characters, the maximum CUID2 length.
is_email() now rejects domain labels that end with a hyphen, such as "user@domain-.com".
is_figi() now rejects the reserved prefixes BS, BM, GG, GB, GH, KY, and VG.
is_ipv6() no longer accepts a trailing single colon after a compressed group, such as "1::2:".
is_isbn() now rejects ISBN-13s that don’t start with 978 or 979, as well as ISMNs (9790).
is_iso_datetime() now validates the timezone offset, rejecting out-of-range values such as "+99:99".
is_ulid() now rejects ULIDs whose first character is greater than 7, which would overflow the 48-bit timestamp.

checkstring 0.2.0

is_color_hex() validates hex color strings (#RGB, #RGBA, #RRGGBB, #RRGGBBAA).
is_ipv6() validates IPv6 address strings, including compressed (::) and IPv4-embedded forms (#18).
is_iso_date() and is_iso_datetime() validate ISO 8601 date and datetime strings.
is_mime() validates MIME type strings against the IANA-registered top-level types.