Fix PyUnicode_AsUTF8AndSize() signature
[`PyUnicode_AsUTF8AndSize()`][1] returns `const char*`, not `char*`.
Fixes #1.
[1]: https://docs.python.org/3/c-api/unicode.html#c.PyUnicode_AsUTF8AndSize
diff --git a/src/VERSION b/src/VERSION
index 99543d9..01c70a3 100644
--- a/src/VERSION
+++ b/src/VERSION
@@ -1 +1 @@
-"0.4.5"
+"0.4.6"
diff --git a/src/_imports.pyx b/src/_imports.pyx
index c4d47a8..5b20993 100644
--- a/src/_imports.pyx
+++ b/src/_imports.pyx
@@ -118,7 +118,7 @@
Py_UCS4 Py_UNICODE_JOIN_SURROGATES(Py_UCS4 high, Py_UCS4 low) nogil
object PyUnicode_FromKindAndData(int kind, const void *buf, Py_ssize_t size)
- char *PyUnicode_AsUTF8AndSize(object o, Py_ssize_t *size) except NULL
+ const char *PyUnicode_AsUTF8AndSize(object o, Py_ssize_t *size) except NULL
object PyDict_SetDefault(object p, object key, object value)