Bump version to 3.2.0

Author: mrkn

ext/bigdecimal/bigdecimal.c

@@ -31,7 +31,7 @@
 #include "bits.h"
 #include "static_assert.h"
 
-#define BIGDECIMAL_VERSION "3.1.9"
+#define BIGDECIMAL_VERSION "3.2.0"
 
 /* #define ENABLE_NUMERIC_STRING */