deprecated method warning; prefer $rr->rdstring()

[pgnd]

these deprecation warning are 'new' (just noticed them); afaict, no ops problems as a result - yet.

perl -v
	This is perl 5, version 36, subversion 1 (v5.36.1) built for x86_64-linux-thread-multi

module_info  Mail::Milter::Authentication
	Name:        Mail::Milter::Authentication
	Version:     undef
	Directory:   /usr/local/share/perl5/5.36
	File:        /usr/local/share/perl5/5.36/Mail/Milter/Authentication.pm
	Core module: no

cpan -D  Mail::Milter::Authentication
	M/MB/MBRADSHAW/Mail-Milter-Authentication-3.20230214.tar.gz
	/usr/local/share/perl5/5.36/Mail/Milter/Authentication.pm
	Installed: 3.20230214
	CPAN:      3.20230214  up to date
	Marc Bradshaw (MBRADSHAW)
	mbradshaw@cpan.org

mail log

	...
	2023-05-11T07:46:39.116458-04:00 mail fm-auth-milter[9352]: Warning: deprecated method; prefer $rr->rdstring() at /usr/local/share/perl5/5.36/Mail/Milter/Authentication/Handler/IPRev.pm line 78.<LF>
	...

[notbrokenjemma]

#141