Release 9.1.9

New features

• Add readonly obfuscated module feature. The plain scripts could read and execute the attributes and functions in the readonly obfuscated module, but could NOT write or change them, refer to
  https://pyarmor.readthedocs.io/en/latest/tutorial/obfuscation.html#using-readonly-module

Fixed isssues

• Fix issue #2204: when printing the basic license information, the note that the basic license need online obfuscation is missed