requirements.txt updated for all versions

Author: Arun S Kumar

requirements.txt

@@ -1,16 +1,16 @@
 coveralls==1.11.1; python_version < '3.4'
-coveralls==2.1.2; python_version > '3.4'
+coveralls==2.1.2; python_version >= '3.4'
 flake8==3.7.9
 flake8-per-file-ignores==0.6
 future==0.18.2
 graphene>=2.1.8,<3
 iso8601==0.1.13
 mongoengine==0.19.1; python_version < '3.4'
-mongoengine==0.20.0; python_version > '3.4'
+mongoengine==0.20.0; python_version >= '3.4'
 mongomock==3.21.0
 pymongo==3.11.0
-pytest==4.6.11; python_version < '3.5'
-pytest==6.1.2; python_version > '3.5'
+pytest==4.6.11; python_version <= '3.4'
+pytest==6.1.2; python_version >= '3.4'
 pytest-cov==2.10.1
 singledispatch==3.4.0.3
 # https://stackoverflow.com/a/58189684/9041712