Add windows and macOS runner, python 3.13 for unit tests

[VigneshVSV]

Some dependencies are breaking OS-specific. This needs to be avoided & should become part of regular testing.

See problem faced in #70 with pyzmq - #70 (comment)

GitHub supports windows and macOS runners, details found here

Rough steps -

• first introduce python 3.13 in the testing matrix
• for each python version, add all three OS-es (mac, windows & linux). So there are total of 9 unit tests.

Even if one OS is included completely (say mac OS is not working because the unit tests were never checked in it), we can create a new sub-issue.