Bump version

Signed-off-by: Jono Yang <jyang@nexb.com>

Author: JonoYang

setup.cfg

@@ -1,6 +1,6 @@
 [metadata]
 name = scancode-toolkit
-version = 31.0.0b5
+version = 31.0.0rc1
 license = Apache-2.0 AND CC-BY-4.0 AND LicenseRef-scancode-other-permissive AND LicenseRef-scancode-other-copyleft
 
 # description must be on ONE line https://github.com/pypa/setuptools/issues/1390