Upgrade psychopg2 to support python >=3.7

Author: mxmeinhold

requirements.txt

@@ -17,7 +17,7 @@ Mako~=1.0.7
 MarkupSafe~=1.0
 mccabe~=0.6.1
 oic~=0.11.0
-psycopg2~=2.7.4
+psycopg2~=2.8.5
 pyldap~=2.4.45
 pylint~=2.3.1
 python-dateutil~=2.6.1