chore: bump to next dev release

Author: dvarrazzo

setup.py

@@ -44,7 +44,7 @@
 # Take a look at https://www.python.org/dev/peps/pep-0440/
 # for a consistent versioning pattern.
 
-PSYCOPG_VERSION = '2.9.8'
+PSYCOPG_VERSION = '2.9.9.dev0'
 
 
 # note: if you are changing the list of supported Python version please fix