ANSPB-423 Fix requirements.

Author: Waldemar Bartikowski

requirements.txt

@@ -1,12 +1,15 @@
-astroid==2.4.1
+astroid==1.6.6 ; python_version < '3'
+astroid==2.4.1 ; python_version >= '3'
 isort==4.3.21
 lazy-object-proxy==1.4.3
-logilab-common==1.6.4
+logilab-common==1.4.4 ; python_version < '3'
+logilab-common==1.6.1 ; python_version >= '3'
 mccabe==0.6.1
 nose==1.3.7
 pycodestyle==2.6.0
-pylint==2.5.2
+pylint==1.9.5 ; python_version < '3'
+pylint==2.5.2 ; python_version >= '3'
 six==1.15.0
 toml==0.10.1
-typed-ast==1.4.1
+typed-ast==1.4.1 ; python_version >= '3'
 wrapt==1.12.1