Add missing GlobalSign root certificate which supports more secure sha25...

...6 algorithm.

Global Sign has three relevant root certificates:

GlobalSign Root R1
GlobalSign Root R2
GlobalSign Root R3

Both R1 and R2 are present, but R3 is missing.

R3 is the more secure root certificate authority that uses SHA256 instead of the degrading SHA1. The root certificate list should be fixed to include all three Global Sign Root certificates.

See article about SHA1's degrading viability as a secure hash algorithm:
https://www.schneier.com/blog/archives/2005/02/cryptanalysis_o.html

For validation here is the source of the certificate: https://support.globalsign.com/customer/portal/articles/1426602-globalsign-root-certificates