mail-client/roundcube: Bump to 1.3.7

mail-client/roundcube: Bump to 1.3.7

Bump to 1.3.7 which addresses EFAIL
(https://github.com/roundcube/roundcubemail/issues/6289). (Bug 662716)

Add an elog statement that gives the location of the post-upgrade
instructions in case the Roundcube update gets buried among many
others. (Bug 462250)

Make dev-php/PEAR-Net_Socket an optional module, and remove redundant
dependencies. (Bug 650792)

Remove references to PEAR modules. (Bug 650910)

Update POST-INSTALL as step 7 is no longer required since we’re using
the complete tarball. (Bug 650912)

Bug: https://bugs.gentoo.org/462250
Bug: https://bugs.gentoo.org/650792
Bug: https://bugs.gentoo.org/650910
Bug: https://bugs.gentoo.org/650912
Closes: https://bugs.gentoo.org/662716
Package-Manager: Portage-2.3.40, Repoman-2.3.9