Changed python req to > 3.8

Author: ForFoxSakes

ci/travis/recipe/meta.yaml

@@ -22,7 +22,7 @@ requirements:
     - python
     - setuptools
   run:
-    - python<3.9  # https://github.com/conda-forge/pyside2-feedstock/issues/56
+    - python>=3.8, <=3.9  # https://github.com/conda-forge/pyside2-feedstock/issues/56
     - arrow
     - brightway2 >=2.1.2
     - bw2io >=0.8