GitPython: Newline injection in config_writer().set_value() enables RCE via core.hooksPath

GitConfigParser.setvalue passes values to Python's configparser without validating for newlines. GitPython's own write converts embedded newlines into indented continuation lines e.g. \n becomes \n\t, but Git still accepts an indented core stanza as a section header — so the injected core.hooksPa...