setup: explicit pandas and Python versions map

It seems that setuptools cannot automatically interpret "install latest
supported by current Python version" directive since it's trying to
install pandas 1.5.0 (supports only Python >= 3.8) for Python 3.6
pipeline.

Part of #238

Author: DifferentialOrange

requirements.txt

@@ -1,4 +1,6 @@
 msgpack>=1.0.4
-pandas
+pandas<=1.1.5 ; python_version <= '3.6'
+pandas<=1.3.5 ; python_version <= '3.7'
+pandas>=1.0
 pytz
 importlib-metadata >= 1.0 ; python_version < '3.8'