patch 8.2.3590: test for v:colornames sometimes fails

Problem:    Test for v:colornames sometimes fails. (Dominique Pellé)
Solution:   Check features.  Clear v:colornames between tests. (Drew Vogel,
            closes #9105, closes #9073)
diff --git a/src/version.c b/src/version.c
index 8e2a10b..e294d8e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -758,6 +758,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3590,
+/**/
     3589,
 /**/
     3588,