[ruby/bigdecimal] Bump up to 3.1.5

https://github.com/ruby/bigdecimal/commit/c47802e813
2023-07-08 18:29:03 +09:00 · 2023-07-08 18:29:03 +09:00 · e501613efa
--- a/ext/bigdecimal/bigdecimal.c
+++ b/ext/bigdecimal/bigdecimal.c
@ -31,7 +31,7 @@
 #include "bits.h"
 #include "static_assert.h"

-#define BIGDECIMAL_VERSION "3.1.4"
+#define BIGDECIMAL_VERSION "3.1.5"

 /* #define ENABLE_NUMERIC_STRING */