patch 8.1.0147: compiler warning when building with Python 3.7

Problem:    Compiler warning when building with Python 3.7.
Solution:   #undef PySlice_GetIndicesEx before redefining it. (Ozaki Kiichi,
            closes #3153)
diff --git a/src/version.c b/src/version.c
index cfc3b23..08a2e04 100644
--- a/src/version.c
+++ b/src/version.c
@@ -790,6 +790,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    147,
+/**/
     146,
 /**/
     145,