support/dependencies/dependencies.sh: require MD5 perl package for netsurf

Fix the following build failure:

Can't locate object method "hexhash" via package "MD5" at utils/git-testament.pl line 47

Fixes:
 - http://autobuild.buildroot.org/results/3dddcbbe7f6ecae5a2db6fac11fb659719452f73



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>