Release 3.7.17.3 version

This is the first 3.7 that supports alt builds.

Author: icanhasmath

Include/patchlevel.h

@@ -23,7 +23,7 @@
 #define PY_RELEASE_SERIAL       0
 
 /* Version as a string */
-#define PY_VERSION              "3.7.17"
+#define PY_VERSION              "3.7.17.3"
 /*--end constants--*/
 
 /* Version as a single 4-byte hex number, e.g. 0x010502B2 == 1.5.2b2.