Addparse_uri() support for Steam TOTP (#153)

Test and documentation improvements

Modify OTP generation to run in constant time (#148)

• Documentation improvements

• Drop Python 3.6 support; introduce Python 3.11 support

Support Steam TOTP (#142)

• Build, test, and documentation updates

Raise default and minimum base32 secret length to 32, and hex secret length to 40 (160 bits as recommended by the RFC) (#115).

• Fix issue where provisioning_uri would return invalid results after calling verify() (#115).

Add optional image parameter to provisioning_uri (#113)

• Support for 7-digit codes in 'parse_uri' (#111)

• Raise default and minimum base32 secret length to 26

parse_uri: Fix handling of period, counter (#108)

• Add support for timezone aware datetime as argument toTOTP.timecode() (#107)

Fix data type for at(for_time) (#85)

• Add support for parsing provisioning URIs (#84)

• Raise error when trying to generate secret that is too short
  (The secret must be at least 128 bits)

• Add random_hex function (#82)