Python: bump minimum version to 3.10

Since Python 3.10 is now supported on all platform,
bump the minimum version to reduce the number of Python versions that
need to be supported simultaneously.

Reviewed By: LazyDodo, sybren, mont29, brecht

Ref D13943

source/blender/python/intern/bpy_capi_utils.h

@@ -20,8 +20,8 @@
 
 #pragma once
 
-#if PY_VERSION_HEX < 0x03090000
-#  error "Python 3.9 or greater is required, you'll need to update your Python."
+#if PY_VERSION_HEX < 0x030a0000
+#  error "Python 3.10 or greater is required, you'll need to update your Python."
 #endif
 
 #ifdef __cplusplus