patch 8.0.0156: not enough test coverage for float functions

Problem:    Several float functions are not covered by tests.
Solution:   Add float tests. (Dominique Pelle)
diff --git a/src/version.c b/src/version.c
index d88c03b..350b4ad 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    156,
+/**/
     155,
 /**/
     154,