There is an ongoing outage on the primary CPAN mirror. It is possible to work around the issue by using MetaCPAN as a mirror.

Revision history for RPi-OLED-SSD1306-128_64

2.3603 2019-06-06
        - MANIFEST.SKIP was preventing us from including a core C file, breaking
          cpan installs with "undefined symbol" error

2.3602  2019-06-05
        - added wiringPi checks in Makefile.PL, so CPAN testers don't go crazy

2.3601  2019-06-05
        First version, released on an unsuspecting world.