dev-ruby/digest: fix tests

Closes: https://bugs.gentoo.org/848018
Signed-off-by: Hans de Graaff <graaff@gentoo.org>

dev-ruby/digest/digest-3.1.0-r1.ebuild

@@ -25,5 +25,5 @@ all_ruby_prepare() {
 }
 
 each_ruby_test() {
-	${RUBY} -Ilib:.:test:test/lib -rhelper -e 'Dir["test/**/test_*.rb"].each{|f| require f}' || die
+	${RUBY} -Ilib:ext/digest/lib:.:test:test/lib -rhelper -e 'Dir["test/**/test_*.rb"].each{|f| require f}' || die
 }