patch 8.1.0201: newer Python uses "importlib" instead of "imp"

Problem:    Newer Python uses "importlib" instead of "imp".
Solution:   Use "importlib" for newer Python versions. (closes #3163)
diff --git a/src/version.c b/src/version.c
index 2d5a131..44c620c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -790,6 +790,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    201,
+/**/
     200,
 /**/
     199,