[Beta] Py36/Py37 Support, dependency conflict resolution

Major changes (v0.1.5)

• Added more workflows to build the torchfl package on different os and python versions before merging it to master.
• Updated the existing workflows to include the checks for all python versions to ensure backward compatibility.
• Removed the usage of Literal type to enable py36, and py37 support.
• Defined a common cache in home dir for torchfl which will be used to store the files instead of the parent dir.