Bump version to 3.3.1 (#443)

* Update changelog for v3.3.1

* Bump version to 3.3.1

Author: tompng

CHANGES.md

@@ -1,5 +1,11 @@
 # CHANGES
 
+## 3.3.1
+
+* All BigMath methods converts non integer precision with to_int
+
+  **@tompng**
+
 ## 3.3.0
 
 * Allow calling to_d without arguments [GH-421]

ext/bigdecimal/bigdecimal.c

@@ -31,7 +31,7 @@
 #include "bits.h"
 #include "static_assert.h"
 
-#define BIGDECIMAL_VERSION "3.3.0"
+#define BIGDECIMAL_VERSION "3.3.1"
 
 /* #define ENABLE_NUMERIC_STRING */