Set for 2.9.0 release (#5149)

python-ligo-lw has had a release which is causing issues when running using latest released version. So lets set up a new released version using igwn-ligolw

Author: GarethCabournDavies

setup.py

@@ -98,8 +98,8 @@ def __getattr__(self, attr):
         vinfo = _version_helper.generate_git_version_info()
     except:
         vinfo = vdummy()
-        vinfo.version = '2.9.dev0'
-        vinfo.release = False
+        vinfo.version = '2.9.0'
+        vinfo.release = True
 
     version_script = f"""# coding: utf-8
 # Generated by setup.py for PyCBC on {vinfo.build_date}.