Fix simple typo: continous -> continuous

[timgates42]

Issue Type

[x] Bug (Typo)

Steps to Replicate

1. Examine Python/PST_function.py, Python/test_script_PST.py.
2. Search for continous.

Expected Behaviour

1. Should read continuous.

Semi-automated issue generated by
https://github.com/timgates42/meticulous/blob/master/docs/NOTE.md

To avoid wasting CI processing resources a branch with the fix has been
prepared but a pull request has not yet been created. A pull request fixing
the issue can be prepared from the link below, feel free to create it or
request @timgates42 create the PR.

https://github.com/timgates42/Image-feature-detection-using-Phase-Stretch-Transform/pull/new/bugfix_typo_continuous

Thanks.